Effectiveness of new legislation on partial sickness benefit on work participation: a quasi-experiment in Finland

Abstract

To examine the effect of the new legislation on partial sickness benefit on subsequent work participation of Finns with long-term sickness absence. Additionally, we investigated whether the effect differed by sex, age or diagnostic category.
A register-based quasi-experimental study compared the intervention (partial sick leave) group with the comparison (full sick leave) group regarding their pre-post differences in the outcome. The preintervention and postintervention period each consisted of 365 days.
Nationwide, individual-level data on the beneficiaries of partial or full sickness benefit in 2008 were obtained from national sickness insurance, pension and earnings registers.
1738 persons in the intervention and 56 754 persons in the comparison group.
Work participation, measured as the proportion (%) of time within 365 days when participants were gainfully employed and did not receive either partial or full ill-health-related or unemployment benefits.
Although work participation declined in both groups, the decline was 5% (absolute difference-in-differences) smaller in the intervention than in the comparison group, with a minor sex difference. The beneficial effect of partial sick leave was seen especially among those aged 45-54 (5%) and 55-65 (6%) and in mental disorders (13%). When the groups were rendered more exchangeable (propensity score matching on age, sex, diagnostic category, income, occupation, insurance district, work participation, sickness absence, rehabilitation periods and unemployment, prior to intervention and their interaction terms), the effects on work participation were doubled and seen in all age groups and in other diagnostic categories than traumas.
The results suggest that the new legislation has potential to increase work participation of the population with long-term sickness absence in Finland. If applied in a larger scale, partial sick leave may turn out to be a useful tool in reducing withdrawal of workers from the labour market due to health reasons.
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Full text

Effectiveness of new legislation on
partial sickness benefit on work
participation: a quasi-experiment in
Finland
Johanna Kausto,
1
Eira Viikari-Juntura,
1
Lauri J Virta,
2
Raija Gould,
3
Aki Koskinen,
1
Svetlana Solovieva
1
To cite: Kausto J, Viikari-
Juntura E, Virta LJ, et al.
Effectiveness of new
legislation on partial sickness
benefit on work participation:
a quasi-experiment in
Finland. BMJ Open 2014;4:
e006685. doi:10.1136/
bmjopen-2014-006685
▸Prepublication history and
additional material is
available. To view these files
please visit the journal
(http://dx.doi.org/10.1136/
bmjopen-2014-006685).
Received 19 September 2014
Revised 18 November 2014
Accepted 19 November 2014
1
Finnish Institute of
Occupational Health, Helsinki,
Finland
2
The Social Insurance
Institution of Finland (SII),
Turku, Finland
3
Finnish Centre for Pensions,
Helsinki, Finland
Correspondence to
Dr Johanna Kausto;
johanna.kausto@ttl.fi
ABSTRACT
Objectives: To examine the effect of the new
legislation on partial sickness benefit on subsequent
work participation of Finns with long-term sickness
absence. Additionally, we investigated whether the effect
differed by sex, age or diagnostic category.
Design: A register-based quasi-experimental study
compared the intervention (partial sick leave) group
with the comparison (full sick leave) group regarding
their pre-post differences in the outcome. The
preintervention and postintervention period each
consisted of 365 days.
Setting: Nationwide, individual-level data on the
beneficiaries of partial or full sickness benefit in 2008
were obtained from national sickness insurance,
pension and earnings registers.
Participants: 1738 persons in the intervention and
56 754 persons in the comparison group.
Outcome: Work participation, measured as the
proportion (%) of time within 365 days when
participants were gainfully employed and did not receive
either partial or full ill-health-related or unemployment
benefits.
Results: Although work participation declined in both
groups, the decline was 5% (absolute difference-in-
differences) smaller in the intervention than in the
comparison group, with a minor sex difference. The
beneficial effect of partial sick leave was seen especially
among those aged 45–54 (5%) and 55–65 (6%) and in
mental disorders (13%). When the groups were
rendered more exchangeable (propensity score
matching on age, sex, diagnostic category, income,
occupation, insurance district, work participation,
sickness absence, rehabilitation periods and
unemployment, prior to intervention and their
interaction terms), the effects on work participation
were doubled and seen in all age groups and in other
diagnostic categories than traumas.
Conclusions: The results suggest that the new
legislation has potential to increase work participation of
the population with long-term sickness absence in
Finland. If applied in a larger scale, partial sick leave
may turn out to be a useful tool in reducing withdrawal
of workers from the labour market due to health
reasons.
INTRODUCTION
The need to increase work participation of
working age people is currently a matter of
concern in many Western countries. In
Finland, delayed or lacking labour market
attachment of young people, absence from
work during later years and early exit from
labour market have all raised alarm. To coun-
teract these trends, an active labour market
policy has been adopted, including the intro-
duction of partial social security benefits and
other tools to increase the so-called flexicurity
of the labour market.
1
In Finland, legislation
on partial sickness benefit was introduced in
2007. The new benefitallowedforthefirst
time to combine part-time sick leave with part-
time work.
TheFinnishsocialinsuranceisbasedonthe
Nordic Model. Everyone aged between 16 and
67, non-retired and living permanently in the
country (employees, self-employed, students,
unemployed job seekers and those on sabbat-
ical or alternation leave) and also non-
residents, working for at least 4 months in
Finland, are covered by statutory sickness insur-
ance. The sickness allowances are financed by
employers, employees and the state; and are
administrated by the Social Insurance
Institution of Finland (SII). Statutory benefits
canrestonpreviousearningsorbenefits or the
Strengths and limitations of this study
▪Applying nationally representative population
register-based data with valid information on the
payment of health-related and unemployment-
related allowances in Finland.
▪Applying a quasi-experimental study design with
difference-in-differences and propensity score ana-
lysis to control for selection on both observed and
unobserved factors.
▪Registers provided only a limited number of
background characteristics.
Kausto J, et al.BMJ Open 2014;4:e006685. doi:10.1136/bmjopen-2014-006685 1
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minimum allowance can be granted. For the earnings-
related occupational sickness benefits, a minimum of
3 months of employment is required.
At present, the Finnish national sickness benefit
scheme includes a full and a partial sickness benefit.
A medical certificate is an absolute requirement for the
two sickness benefits to be granted. In order to be eligible
for the partial benefit, an employee has to be eligible for
a full benefit as well, but according to medical judge-
ment, partial return to work (RTW) is safe enough.
Partial sick leave is thus alternative to full sick leave and it
is always medically certified. During the first years after
introducing the partial sickness benefit in Finland, a
partial sick leave had to be directly preceded by a period
of full sick leave of at least 60 days and the partial sickness
benefit could be granted from a minimum of 12 to a
maximum of 72 working days. During partial sick leave,
work time and salary are reduced by 40–60% of the
regular and work tasks can be modified, if necessary. The
employee and the employer sign a fixed-term work con-
tract for the part-time work. In Finland, the use of partial
sick leave is voluntary for the individual. The employer, as
well, is entitled to decline the use of the benefit in case
the work arrangements needed at the work place are not
feasible.
Sickness absence rates are in many countries higher
among women compared with men.
2
Also, partial sick
leave has been more frequently used by women.
3
It is
known that sickness absence increases with age.
2
It is also
recognised that challenges of RTW are different, for
example, in musculoskeletal diseases and mental disor-
ders. In the latter category, the outflow from disability ben-
efits due to recovery has been lower.
4
The current evidence on the effects of partial sick leave
on RTWor work participation is partly inconsistent. In the
other Nordic countries, partial sick leave has been found
to increase the likelihood of return to regular working
hours
56
and to be associated with higher subsequent
employment rate.
7
No effect of active sick leave (RTW to
modified duties) on the average number of sick leave days
or long-term disability had been detected in a Norwegian
cluster randomised controlled trial.
8
There is some dis-
crepancy in the findings on the effectiveness of partial sick
leave in mental disorders. A Danish study
9
found no
effect, whereas a Swedish study
10
reported a weak effect of
partial sick leave on full recovery in the beginning of work
disability due to mental disorders, and a stronger effect
when partial sick leave was assigned after 60 days of full
sick leave.
In a randomised controlled trial among persons with
musculoskeletal disorders, we found that early part-time
sick leave predicted faster sustained RTW than full sick
leave.
11
The beneficial effect of partial sick leave on work
retention was also observed at population level.
12 13
Partial
sick leave was associated in the short term with decreased
work retention, in terms of increased subsequent sickness
absence. In the long-term it was associated with increased
work retention, in terms of increased subsequent use of
partial disability pension and decreased use of full disabil-
ity pension. These findings imply the necessity to use an
outcome that simultaneously accounts for different indica-
tors of work participation. Some of these previous observa-
tional studies have suffered from limited data samples and
narrow generalisability of findings,
59
self-reported data
9
and incomprehensive operationalisation and measure-
ment of work participation.
56101213
In order for policymakers to be able to make well-
informed decisions in the area of social and health pol-
icies, scientific evaluation of the effectiveness of
population-level interventions, for example, introducing
new legislation or policy change is needed.
14
Natural or
quasi-experiments have successfully been used in con-
nection with various population-level interventions in
the field of public health when planned experimenta-
tion, that is, manipulation of exposure, has not been
possible.
15
In the field of work-disability research, this
approach has, however, been rare.
2
This study examined the effects of the new Finnish legis-
lation that enabled the use of partial sickness benefiton
subsequent work participation. For this, we compared
beneficiaries of partial sickness benefit with those receiv-
ing full sickness benefit a year after the law on partial sick
leave was enacted. We utilised a quasi-experimental design
with an integrated measure of work participation. Analyses
were carried out in an individual-level register-based data
representative of the Finnish working population with
long-term sickness absence. We examined whether the
effects of partial sick leave on subsequent work participa-
tion differed by sex, age or diagnostic category of the
benefit receivers.
METHODS
Study design and setting
The population-level intervention of interest in this
study was the introduction of partial sick leave in
Finland in 2007. We conducted a quasi-experimental
study following recent guidelines on evaluating popula-
tion health interventions.
15
This design was chosen to
minimise the effect of measured and unmeasured con-
founding. We compared the intervention (partial sick
leave) group with the comparison (full sick leave) group
regarding their pre-post differences in work participa-
tion. The preintervention (T1) and postintervention
(T2) study period each consisted of 365 days. A wash-out
period of 1 year was set preintervention and postinter-
vention (figure 1) in order to obtain a robust effect of
the intervention on work participation. These time
windows were allowed to move according to the timing
of the individual’s sick leave period.
Individual-level data were derived from the national
sickness insurance register of the SII and the pension
and earnings registers of the Finnish Centre for Pensions.
Data from these three registers were linked on the basis
of social security numbers of the participants. The social
insurance register provided information on all medically
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certified and compensated sickness absence spells, tem-
porary and permanent national disability pensions, and
old-age pensions in Finland. The registers of the Finnish
Centre for Pensions contained information on employ-
ment periods, earnings-related pensions and unsalaried
periods due to disability, rehabilitation or unemploy-
ment. Written consent from the individuals was not
needed as only encrypted register data were obtained by
the researchers carrying out the analyses in the Finnish
Institute of Occupational Health.
Participants
Participants that were granted a partial sickness benefit
(intervention group) were compared with those who
received a full sickness benefit (comparison group). A
total sample of individuals who had received either
partial sickness benefit (n=1838) or full sickness benefit
(n=67 086) in 2007–2008 and whose compensated sick-
ness absence period had ended between 1 January and
31 December 2008 was drawn from the national sickness
insurance register. Since a full-time sickness absence of
60 working days had to precede a partial sick leave, only
those with full sick leave ending with an uninterrupted
period of at least 60 days of payment of the benefit were
included in the total sample. Thus, in our sample, recei-
vers of full sickness benefit had not received partial sick-
ness benefit, but they would have been entitled to it as
for the length of the preceding fulltime sickness absence.
Since eligibility for a partial sickness benefit required
a prior work contract, we excluded from the analyses
those who did not have any employment periods (n=2
and n=4923) during the entire study period. We add-
itionally excluded those who had died (n=24 in the
partial sick leave group and n=2600 in the full sick leave
group) or moved to old age pension (n=1 and n=354,
respectively), had not turned 16 at the time of the first
data collection period (T1; n=3) or whose sickness
absence periods (ending in 2008) extended beyond the
time frame of data collection (n=66 and n=1024). The
final sample included 1738 participants in the partial
sick leave group and 56 754 participants in the full sick
leave group. We focused our analyses in the four main
diagnostic groups in which partial sickness benefit has
most frequently been used, that is, musculoskeletal dis-
eases, mental disorders, traumas and tumours (M, F, S
and T, and C and D categories in ICD-10, respectively).
All other diagnoses were merged in one group.
Outcome measure
Work participation was operationalised as the time the
individuals were likely to have actually participated in
gainful employment. It was approximated as the propor-
tion (%) of time within 365 days when participants had
an employment contract and did not receive either
partial or full ill-health-related benefits (sickness bene-
fits, rehabilitation allowances, disability pensions), or
unemployment benefits. Work participation was calcu-
lated for T1 and T2. It was assumed that when receiving
partial benefits, the participants worked half of the work
time (which is typically the case in Finland).
Covariates
Data on sex, dates of birth and death, insurance district
(region), annual gross income in 2007, diagnostic codes
(ICD-10) and occupational branch were obtained from
the sickness insurance register. Information on occupa-
tion was available for all participants in the intervention
group and for a random sample of 7.7% of the partici-
pants in the comparison group.
Data analyses
The distributions of all variables were compared between
the total full sickness benefit group (n=67 086) and the
subsample of those participants in the full sickness
benefit group for whom the registers provided informa-
tion on occupational branch (n=4347). Since no differ-
ences in the distributions were detected, we assumed that
information on occupational branch was missing at
random. Multiple imputation was used to compensate for
the missing data on occupational branch in the compari-
son group. For this, we generated multiple-imputed data
sets (n=10) using the proc mi of SAS. The imputation
model included all covariates.
Propensity score (PS) with 1:1 matching was used to
match individuals on the probability that they would
belong to the intervention (partial sick leave) group.
Individuals that were matched to each other had equal
or nearly equal (close enough) estimated PSs.
Difference-in-differences (DID) and PS analyses are
methods that are complementary to each other and can
be applied in causal inference to counter selection bias
Figure 1 Schematic presentation of the study design and
difference-in-differences method. (T1 corresponds to
preintervention period, T2 corresponds to postintervention period).
Kausto J, et al.BMJ Open 2014;4:e006685. doi:10.1136/bmjopen-2014-006685 3
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and confounding.
16
We applied the DID method alone
and in combination with PS matching. Combining
methods to counter bias and confounding from differ-
ent sources and comparing the results have been
encouraged.
15
The DID method can be applied to
control the fixed unobserved individual differences and
common trends.
The DID method allows one to estimate the difference
in pre-post, within participant, differences between the
intervention and the comparison group. The effect of
partial sick leave on work participation was consequently
estimated as the difference in pre-post differences (dif-
ferences between T2 and T1) between partial and full
sick leave groups. The effect was estimated using the
general linear model (GLM) with repeated measures
design. An F-statistic for the interaction term between
the group assignment and change of work participation
in time was applied as the DID statistic.
PS is defined as a conditional probability of being
exposed to a certain intervention given observed covari-
ates.
15 17 18
It is applied to balance the covariates in two
groups and thus to reduce bias. We computed PS (ie,
probability of being exposed to partial sick leave) by logis-
tic regression for all participants. The following set of
variables and their interaction terms were included in the
logistic regression model: age, sex, diagnostic category,
income, occupation, insurance district, and work partici-
pation, sickness absence, rehabilitation periods and
unemployment at T1. The best fit model was chosen.
Thereafter, we matched the partial sick leave and full sick
leave groups on the estimated PS using local optimal
(greedy) algorithm.
19
The matching was performed within
(sex × diagnostic category) strata. Subsequently a DID ana-
lysis was also carried out in the matched subsample.
Several sensitivity analyses were carried out. The ana-
lyses were run separately for participants for whom the
registers provided information on occupational branch
and for the total sample in which imputed data on occu-
pational branch were utilised for the comparison group.
To examine the group difference in work participation
at T1 (due to unemployment or sick leave) as source of
reduced group comparability, the analyses were carried
out separately among participants who did not receive
unemployment benefits at T1 and among participants
with 100% of work participation at T1.
RESULTS
Descriptive characteristics of the study population
Information on the background characteristics of the
intervention and comparison group in the total analysed
sample is shown in table 1. Women constituted 71% of
the partial sick leave group and 53% of the full sick
leave group. Partial benefit was most common among
those who were aged between 35 and 54, whereas full
benefit was common among those aged from 45 to 65.
The income level of those in the partial sick leave group
was higher than of those in the full sick leave group.
The partial sickness benefit was most often used in con-
nection with mental disorders and musculoskeletal dis-
eases, while the full benefit was most often used in
musculoskeletal diseases. The use of the partial benefit
was most frequent in social and healthcare services and
administrative and office work, whereas the full benefit
was most commonly used in industrial and service work.
No large regional differences in the use of the benefits
were detected.
DID in work participation between partial and full sick
leave group
In both groups the level of work participation decreased
during the follow-up, the absolute reduction being
larger in the full sick leave group (−26.5%) as compared
with the partial sick leave group (−21.2%; table 2). The
absolute overall DID in work participation was 5.3%
(95% CI 3.1% to 7.5%).
The DID in work participation tended to be larger in
men than in women.
In all age categories, work participation declined
more in the full than in the partial sick leave group. The
difference in the decline was significant in age categor-
ies 45–54 and 55–65. There was no effect in those aged
35–44. In the youngest age category (16–34 years) the
DID was large but statistically non-significant.
A statistically significantly larger effect (12.8%, 95% CI
9.0% to 16.5%) was found in mental disorders as com-
pared with the other diagnostic categories.
The results found in the subsample of participants for
whom the registers provided information on occupa-
tional branch were very similar to those in the total
sample (data not shown). The exclusion of the partici-
pants who received unemployment benefits at T1 led to
an absolute increase in the DID in work participation
(DID 7.6%, 95% CI 5.4% to 9.7%). The DID in work par-
ticipation increased further (DID 9.5%, 95% CI 6.8% to
12.1%) when participants with reduced work participa-
tion (for any reason) at T1 were excluded from the
analyses.
DID in work participation in the PS-matched subsample
The matching procedure resulted in a total of 1660
matched pairs of participants. The PS matched partial
sickness benefit receivers did not differ from full sick-
ness benefit receivers with regard to age, gross income,
number of unemployment days, sickness absence days,
rehabilitation days or work participation at T1. There
were some differences between the groups in the distri-
bution of occupational branches and insurance districts
(see online appendix table 1).
The results from the DID analysis in the PS-matched
subsample are presented in table 3. The absolute overall
DID was increased to 9.8% (95% CI 5.9% to 13.7%). A
tendency for a larger DID in men than in women was
also found in this subsample. The DID was still the
largest in those participants aged over 45 years, but in
contrast to the total sample an effect was seen in the
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younger age categories as well. Differences between the
diagnostic categories were reduced as compared to the
total sample. The largest effect was still found in mental
disorders. In addition, a statistically significant DID was
also found in musculoskeletal diseases and tumours.
Further adjustment for the differences in the distribu-
tion of occupation and insurance district between the
intervention and comparison group had no effect on
the results of the DID analysis.
DISCUSSION
Principal findings
We applied a quasi-experimental design to study the
population-level effects of the introduction of partial
sickness benefit in Finland among a working population
with long-term sickness absence. It was found that
partial sick leave had a positive effect on work participa-
tion. Although the overall work participation declined
from T1 to T2, at the population level the decline was
5% (absolute difference) smaller among the receivers of
partial sickness benefit (intervention group) than
among the receivers of full sickness benefit (comparison
group). The beneficial effect of partial sick leave was
seen especially among those aged between 45–54 and
55–65 and in mental disorders. No major sex difference
was detected. When the groups were rendered more
exchangeable, the effect on work participation was
doubled, and the effects were seen in other diagnostic
categories than traumas and all age groups.
Validity of the study
An observational quasi-experimental study design can be
applied to assess the effects of a planned event or inter-
vention, when randomised controlled trials are neither
ethical nor feasible. Observational studies can also
better simulate real-world settings and offer more rele-
vant information in view of policy-making.
20
The
internal validity of observational studies is lower than
that of randomised controlled trials due to possible
Table 1 Characteristics of participants in partial and full sick leave group at the time of intervention (n, %)
Partial sick leave n=1738 Full sick leave n=56 754
Sex (%)
Female 1236 (71.1) 30 058 (53.0)
Age (years) (%)
16–34 217 (12.5) 10 901 (19.2)
35–44 430 (24.7) 11 231 (19.8)
45–54 753 (43.3) 18 740 (33.0)
55–65 338 (19.5) 15 882 (28.0)
Mean (SD) 46.2 (9.0) 45.7 (11.3)
Annual gross income (€) (%)
−30 000 1237 (71.2) 46 119 (81.3)
30 001–60 000 409 (23.5) 9593 (16.9)
60 001–39 (2.2) 732 (1.3)
Missing 53 (3.1) 310 (0.5)
Median 24 618 20 668
Diagnostic categories (%)
Mental disorders 663 (38.2) 14 255 (25.1)
Musculoskeletal diseases 624 (35.9) 20 613 (36.3)
Tumours 112 (6.4) 3031 (5.4)
Traumas 136 (7.8) 8416 (14.8)
Other 203 (11.7) 10 439 (18.4)
Insurance district (%)
Northern 219 (12.6) 7764 (13.7)
Western 259 (14.9) 7824 (13.8)
Eastern 194 (11.2) 8525 (15.0)
South-Western 410 (23.6) 13 254 (23.3)
Southern 656 (37.7) 19 349 (34.1)
Missing 0 (0.0) 38 (0.1)
Occupational branch (%) (non-imputed subsample n=4347)
Technical and scientific work, etc 193 (11.1) 409 (9.4)
Social and healthcare services 516 (29.7) 719 (16.5)
Administration and office work 293 (16.9) 413 (9.5)
Commercial work 113 (6.5) 288 (6.6)
Agriculture and forestry 50 (2.9) 214 (4.9)
Transport 60 (3.4) 269 (6.2)
Industrial and construction work, mining 309 (17.8) 1146 (26.4)
Service work 204 (11.7) 889 (20.5)
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Table 2 Comparison of work participation (%) between partial and full sick leave group (GLM repeated measures design)
Work participation (%)
n
Preintervention
period (T1)
Mean (95% CI)
Postintervention
period (T2)
Mean (95% CI)
Post-pre
difference (T2-T1)
Mean (95% CI) p Value
Difference in
differences
Mean (95% CI) F-statistic p Value
All*
Partial sick leave 1685 86.6 (85.2 to 88.1) 65.4 (63.4 to 67.4) −21.2 (−23.4 to −19.1) 0.001 5.3 (3.1 to 7.5) 22.8 0.001
Full sick leave 56 406 79.4 (79.1 to 79.6) 52.9 (52.5 to 53.2) −26.5 (−26.9 to −26.2) 0.001
Males†
Partial sick leave 490 86.6 (84.0 to 89.1) 62.7 (59.0 to 66.5) −23.9 (−27.9 to −19.9) 0.001 6.3 (2.3 to 10.3) 9.3 0.002
Full sick leave 26 507 80.3 (80.0 to 80.7) 50.2 (49.7 to 50.7) −30.1 (−30.7 to −29.6) 0.001
Females†
Partial sick leave 1195 85.4 (83.7 to 87.0) 66.9 (64.6 to 69.3) −18.4 (−21.0 to −15.9) 0.001 4.9 (2.4 to 7.5) 14.2 0.001
Full sick leave 29 889 78.6 (78.2 to 78.9) 55.2 (54.7 to 55.7) −23.4 (−23.9 to −22.9) 0.001
16–34 years*
Partial sick leave 210 89.3 (85.8 to 92.8) 75.5 (70.2 to 80.9) −13.8 (−19.6 to −8.0) 0.001 2.8 (−1.1 to 10.6) 2.5 0.111
Full sick leave 10 759 84.6 (84.1 to 85.1) 66.1 (65.3 to 66.8) −16.6 (−20.8 to −12.5) 0.001
35–44 years*
Partial sick leave 424 84.7 (81.9 to 87.5) 68.1 (64.2 to 72.0) −16.6 (−20.8 to −12.5) 0.001 2.0 (−2.2 to 6.2) 0.9 0.352
Full sick leave 11 177 78.4 (77.9 to 79.0) 59.8 (59.1 to 60.5) −18.6 (−19.4 to −17.8) 0.001
45–54 years*
Partial sick leave 725 86.9 (84.7 to 89.0) 65.7 (62.6 to 68.8) −21.1 (−24.4 to −17.9) 0.001 4.7 (1.4 to 8.0) 7.9 0.005
Full sick leave 18 659 77.6 (77.2 to 78.1) 51.8 (51.2 to 52.4) −25.9 (−26.5 to −25.2) 0.001
55–65 years*
Partial sick leave 326 89.6 (86.3 to 92.9) 57.0 (52.3 to 61.7) −32.6 (−37.7 to −27.5) 0.001 5.7 (0.5 to 10.8) 4.7 0.030
Full sick leave 15 811 78.5 (78.0 to 78.9) 40.2 (39.5 to 40.8) −38.3 (−39.0 to −37.6) 0.001
Musculoskeletal diseases‡
Partial sick leave 598 87.0 (84.8 to 89.3) 60.3 (57.0 to 63.6) −26.7 (−30.3 to −23.2) 0.001 0.7 (−2.9 to 4.3) 0.1 0.712
Full sick leave 20 537 79.7 (79.4 to 80.1) 52.3 (51.7 to 52.9) −27.4 (−28.0 to −26.8) 0.001
Mental disorders‡
Partial sick leave 645 84.6 (82.2 to 87.1) 67.0 (63.8 to 70.3) −17.6 (−21.3 to −13.9) 0.001 12.8 (9.0 to 16.5) 43.8 0.001
Full sick leave 14 136 74.6 (74.0 to 75.1) 44.2 (43.5 to 44.9) −30.4 (−31.1 to −29.6) 0.001
Traumas‡
Partial sick leave 132 86.7 (82.0 to 91.3) 68.1 (61.5 to 74.6) −18.6 (−25.3 to −11.8) 0.001 −3.2 (−10.0 to 3.5) 0.9 0.348
Full sick leave 8312 82.9 (82.3 to 91.3) 67.6 (66.7 to 68.4) −15.3 (−16.2 to −14.5) 0.001
Tumours‡
Partial sick leave 109 90.6 (85.9 to 95.4) 75.0 (67.4 to 82.5) −15.7 (−23.5 to −7.9) 0.001 5.3 (−2.6 to 13.2) 1.7 0.190
Full sick leave 3021 87.2 (86.3 to 88.1) 66.2 (64.8 to 67.6) −21.0 (−22.4 to −19.5) 0.001
Other diagnostic categories‡
Partial sick leave 201 87.4 (83.4 to 91.4) 63.6 (57.8 to 69.4) −23.8 (−30.0 to −17.6) 0.001 6.2 (−0.05 to 12.5) 3.8 0.052
Full sick leave 10 400 80.2 (79.6 to 80.7) 50.1 (49.3 to 50.9) −30.0 (−30.9 to −29.2) 0.001
*Age, sex, income, diagnosis, occupational group, insurance district.
†Age, income, diagnosis, occupational group, insurance district.
‡Age, sex, income, occupational group, insurance district.
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selection according to exposure. For this reason, an
analytical approach called potential outcomes or coun-
terfactual framework was chosen. The term refers to the
fact that in an ideal situation the exposed would be
compared to themselves when unexposed. Since this
comparison is impossible, we need a comparable or
exchangeable comparison group. We utilised two
methods (DID and PS) that have been previously recom-
mended and applied to control for selection on both
observed factors and unobserved fixed factors.
15 20 21
In the DID method, it is assumed that the unobserved
characteristics in the studied groups are stable and that
the outcomes would change identically in these groups
in the absence of intervention. Consequently, the inter-
vention and comparison groups should be identical,
except for the intervention status. However, it is suffi-
cient that the groups are closely, though not exactly,
similar.
15
We included in the comparison group only
participants who would have been entitled to partial
sickness benefit as for the length of the preceding sick-
ness absence. We also applied a short wash-out period,
to minimise the intragroup differences between the two
time points. However, as full information on the eligibil-
ity of the participants for partial sickness benefit was not
available in the registers (eg, severity of the health
problem and degree of remaining workability), we uti-
lised matching on PS to further increase the exchange-
ability of the groups. Moreover, at the time of the study,
the national rates in sickness absence were rather stable.
The unemployment rate in Finland was relatively low
during the intervention in 2008 (6.4%), however the
rates were similar at T1 (7.7–8.4%) and T2 (7.8–8.4%).
We utilised nationwide population data with compre-
hensive individual-level register-based information on
ill-health-related and unemployment-related absences
from work. Personal identification (social security)
numbers enabled linking information from three differ-
ent source registers. These registers have originally been
established for administrative purposes, but the data can
also be used for research.
22
Among the advantages of
register-based studies is a low likelihood of selection and
attrition bias. The source registers of this study provided
valid information on the receivers and payment days of
the benefits. A limitation of the registers is that they typ-
ically provide only a limited number of background
characteristics of the participants and other covariates.
The process of assignment to partial sick leave is not
random. Most likely it is complex and affected by many
actors (the patient, physician, employer and workplace)
for which information cannot be found in the national
registers. Nevertheless, the factors that were included in
the analyses have earlier been found to be important
predictors of the use of health-related social security
benefits and also associated with work disability and
RTW.
Information on diagnoses for sickness benefits was also
retrieved from registers and had been based on medical
assessment. In case of a long-term sickness absence
(lasting more than 60 days) in Finland, the sickness
benefit is paid in shorter periods, each being covered
with a separate medical certificate. Diagnostic codes are
transferred from these certificates to the administrative
registers. We used the latest (and presumably the most
accurate) diagnostic code provided for each long-term
sickness absence in 2007–2008. Data on occupational
branch had to be imputed for the majority of participants
in the comparison group. Nevertheless, the sensitivity
analyses suggested that using imputed data on occupa-
tion did not affect the results. In contrast to earlier
studies on the topic, work participation was approxi-
mated in the current study by taking simultaneously into
account the rate of different ill-health-related and
Table 3 Comparison of work participation (%) between partial and full sick leave group
Work participation (%)
n (pairs)
Difference in differences
Mean (95% CI) F-statistic p Value
All* 1660 9.8 (5.9 to 13.7) 60.8 0.0001
Males†489 12.4 (6.9 to 17.9) 28.1 0.002
Females†1171 7.2 (3.1 to 11.4) 34.0 0.0001
16–34 years* 209 8.5 (0.5 to 16.6) 9.5 0.002
35–44 years* 422 6.7 (0.7 to 12.6) 9.8 0.002
45–54 years* 708 11.1 (6.3 to 15.9) 30.3 0.0001
55–65 years* 321 12.9 (6.5 to 19.4) 12.2 0.001
Musculoskeletal diseases‡598 6.3 (1.5 to 11.2) 6.0 0.015
Mental disorders‡621 18.9 (14.2 to 23.5) 59.9 0.0001
Traumas‡131 0.3 (−9.3 to 9.9) 0.0 0.99
Tumours‡109 12.5 (1.8 to 23.2) 5.9 0.016
Other diagnostic categories‡201 11.1 (3.3 to 18.9) 7.6 0.006
(GLM repeated measures design) in the PS-matched subsample.
*Age, sex, income, diagnosis, occupational group, insurance district.
†Age, income, diagnosis, occupational group, insurance district.
‡Age, sex, income, occupational group, insurance district.
PS, propensity score.
Kausto J, et al.BMJ Open 2014;4:e006685. doi:10.1136/bmjopen-2014-006685 7
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unemployment-related benefits. We operationalised work
participation as proportion of time within a year of not
receiving ill-health-related or unemployment benefits.
Hence, we had a relatively comprehensive indicator of
the availability of the participants for the labour market.
Results in relation to earlier findings
The overall results of this study are congruent with earlier
findings, indicating positive effects of partial sick leave on
RTW and work retention.
5–712
We found that partial sick
leave had a positive effect on future work participation
especially in mental disorders, but the results of the ana-
lyses in the subgroup suggested that the overall effect in
the total sample might be underestimated.
Our findings on the usefulness of partial sick leave in
mental disorders, though not directly comparable, are
congruent with a study showing the beneficial effects of
partial sick leave on RTW in mental disorders after 60 days
of full sick leave,
10
but differ from an earlier study report-
ing no effect.
9
The literature suggests that returning and
continuing at work may be more challenging for those
with mental disorders than those with somatic problems
(eg, musculoskeletal diseases).
23–25
In addition, the
outflow from disability benefits due to recovery has been
lower among those with mental disorders than with muscu-
loskeletal diseases.
4
However, in our previous study we
found an effect of partial sick leave on work disability
pension in both diagnostic categories, the effect tending
to be larger in mental disorders than in musculoskeletal
diseases.
12
The diagnostic groups of musculoskeletal dis-
eases and mental disorders may differ in the degree of
comparability of the partial and full sick leave groups with
regard to the background characteristics, severity of the
health problem and remaining work ability, number of
sickness absences as well as in transition to rehabilitation
and unemployment. When the exchangeability of the
groups was increased with PS matching, a beneficial effect
on work participation was detected also in persons with
musculoskeletal diseases and those with tumours.
Sickness absence is known to increase with age.
26
In
addition, it has been found that RTW after long-term sick-
ness absence is less likely at higher ages.
27 28
Partial sick
leave was found to be most frequently used and also most
effective among middle-aged and older workers. It may
well be that work arrangements associated with partial
sick leave are more easily implemented by employees in a
more established or stable work situation.
CONCLUSIONS
The overall results of the effectiveness of partial sick
leave on work participation suggest that the new legisla-
tion on partial sickness benefit introduced in 2007 has
the potential to increase work participation of the
working population with long-term sickness absence in
Finland. A positive effect was seen especially in mental
disorders. In the future—if applied in a larger scale—
partial sick leave may turn out to be an effective tool in
reducing temporary and permanent withdrawal of
workers from the labour market due to health reasons.
Contributors JK, SS, EV-J, LJV and AK designed the study. All authors were
involved in data collection. JK, SS and AK conducted the analyses, all
contributed to the interpretation of the results and JK, SS and EV-J drafted
the manuscript. All authors accepted the final version of the manuscript.
Funding The study received financial support from the Social Insurance
Institution of Finland (grant no: 67/26/2011).
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
Open Access This is an Open Access article distributed in accordance with
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which permits others to distribute, remix, adapt, build upon this work non-
commercially, and license their derivative works on different terms, provided
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quasi-experiment in Finland
sickness benefit on work participation: a
Effectiveness of new legislation on partial
Koskinen and Svetlana Solovieva
Johanna Kausto, Eira Viikari-Juntura, Lauri J Virta, Raija Gould, Aki
doi: 10.1136/bmjopen-2014-006685
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