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Journal of Occupational Rehabilitation, Vol. 12, No. 1, March 2002 (© 2002)
The Reduction of Chronic, Nonspecific Low Back Pain
Through the Control of Early Morning Lumbar Flexion:
3-Year Follow-Up
Stover H. Snook,
1,4
Barbara S. Webster
2
, and Raymond W. McGorry
3
Three years ago, an 18-month randomized controlled trial of chronic, nonspecific low back
pain investigated the effectiveness of instructing subjects to restrict bending activities in the
early morning, when the fluid content in the disc is increased. Pain days (as recorded by
daily diaries) were reduced 23% in the treatment group, compared to a 2% reduction in the
control (sham treatment) group. The purpose of the current follow-up study was to determine
whether the results of that trial were maintained during the 3 years following completion of
the trial. A questionnaire was mailed to the 60 subjects who completed the original trial. Fifty
subjects completed the questionnaire for a response rate of 83%. Thirty-one subjects (62%)
continued to restrict bending activities in the early morning, and experienced a further
reduction of 10.1 pain days per month (51%) since the completion of the experiment.
However some of the subjects who did not continue to comply also improved. Several
possible explanations for the improvement of noncompliant subjects are offered.
KEY WORDS: low back pain; intervertebral disc; disc hydration; self-care.
INTRODUCTION
Two recent studies in New Zealand have demonstrated the effect of hydration on the
mechanical properties of the intervertebral disc. Using a bovine model, Race et al.
demonstrated that the compressive stiffness of the disc, and the ability of the disc to dissipate
energy, are effected by the degree of disc hydration (1). In a follow-up study using the same
bovine model, Simunic
et al. demonstrated that healthy discs compressed while fully flexed
and fully hydrated are highly susceptible to intra-anular prolapse through an existing anular
division (2).
The above studies are consistent with earlier in vivo and in vitro studies conducted by
Adams
et al. in the United Kingdom (3,4). The investigators concluded that there is an
1
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts.
2
Liberty Mutual Center for Disability Research, Hopkinton, Massachusetts.
3
Liberty Mutual Research Center for Safety and Health, Hopkinton, Massachusetts.
4
Correspondence should be directed to Stover H. Snook, 10472 S.E. Amberjack Ct., Hobe Sound, Florida 33455;
e-mail: stover@att.net.
13
1053-0487/02/0300-0013/0 © 2002 Plenum Publishing Corporation
increased risk of injury (sudden prolapse) to the lumbar discs when a person bends forward in the early
morning, primarily because of the increased hydration of the disc at that time. It was estimated that
the bending stresses are three times greater in the early morning than they are later in the day. The
question was asked "Is this likely to be of any clinical significance?"
A randomized controlled trial conducted by Snook
et al. in the United States attempted to answer
that question, not for disc prolapse, but for chronic, nonspecific low back pain (5). Sixty subjects with
an average du
r
ation of pain of 16.75 years completed the trial. The trial lasted for 18 months (see Fig.
1). Baseline data were collected during the first 6 months. During the second 6 months (Phase 1),
subjects were randomly divided into treatment and control groups.
The treatment group received instructions in restricting bending activities in the early morning.
Subjects were told that the first 2 h after rising was the most important time to protect and maintain a
straight back. Getting out of bed without flexing the back was demonstrated. Once standing, subjects
were instructed not to bend, squat or sit for the first 2 h. but that standing and walking were allowed.
Subjects were told that sitting, squatting or kneeling with a straight back was permissible after the first
2 h. but to avoid actual bending. After 4 h, moderate activity with slight bending was allowed. After 6
h, subjects were allowed to perform usual activities, but were told to avoid extreme bending. The
difficulties in complying with this schedule were discussed, and advice was given for performing
activities of daily living. Subjects were told that partial compliance with the schedule was better than
no compliance.
The control (sham treatment) group received instructions in a series of commonly prescribed
exercises (pelvic tilt, modified sit-up, double knee to chest, hamstring stretch, side leg raise, and cat
and camel) found by Faas
et al. to be ineffective in reducing low back pain (6). Each control group
subject was given written instructions and a personal videotape demonstrating the exercises.
Approximately 45 min were spent in training each treatment group and control group subject (see
Snook
et al. (5) for more detailed descriptions of treatment and control group instructions). The final
6 months (Phase 2) included a crossover in which the control group received the experimental
treatment.
14 Snook, Webster, and McGorry
Pain intensity (as recorded by daily diaries) was reduced by 29% in the treatment group,
compared with a 6%a reduction in the control group (p < 0.01). Days in pain were reduced
23`70 in the t
r
eatment group, compared with a 2% reduction in the control group (p < 0.05).
After receiving the experimental treatment, the control group responded with smaller, but
significant, reductions in pain intensity and pain days
(p < 0.05). Significant reductions were also observed for disability, impairment, and
medication usage.
The purpose of this follow-up study was to determine whether the results were main-
tained during the 3 years following the completion of the trial.
METHOD
A one-page questionnaire was mailed to each of the 60 subjects who completed the
original t
r
ial. The questionnaire contained the following questions.
1. Has the concept of flex management (restricting bending activities in the early
morning) been useful to you in controlling your low back pain? Yes or No.
2. Do you currently restrict your bending activities in the early morning? Yes or No.
3. How many pain-free days can you recall in the past month?
Subjects were asked to answer as honestly as they could. As stated in the questionnaire, "It is
more important to he honest than to try to please us"
The recall period of 1 month in Question 3 was based upon a study by McGorry ct al.
that investigated the accuracy of low back pain recall (7). The data for the recall study were
collected during the exit interviews of the randomized controlled trial described above. During
the interview. each subject was asked, without elaboration by the researcher, to recall the
number of pain-free days in the past week, the past month, and the past 6 months. The recall
data were then compared with the daily reports of pain contained in each subject
'
s diary.
Subjects slightly overestimated the number of pain-free days for the 1-week period, and
significantly underestimated (p < 0.0003) the number of pain-free days for the 6-month period.
The 1-month recall of pain was essentially the same as the daily diary reports.
RESULTS
Fifty subjects completed and returned the questionnaire for a response rate of 83%.
Thirty-three subjects (66%) reported that the concept of flex management (restricting bending
activities in the early morning) was useful in cont
r
olling low hack pain. Thirty-one subjects
(62(% ) reported that they continue to restrict bending activities in the early morning.
The results from Question 3 are contained in Table I. The pain-free days per month
reported by the subjects were converted into pain days per month by subtracting pain-free
days from 30.33 (the average number of days per month in a 6-month period). Three years
after completing the 6-month experimental intervention, 37 subjects (74%) reported further
reductions in pain days per month. The mean reduction was 13.8 pain days per month. Two
subjects (4%) reported no change in pain days per month. Eleven subjects (22%) reported
Reduction of Chronic, Nonspecific Low Back Pain—3-Year follow-Up 15
1
a mean increase of 5.2 pain days per month. The mean change for the entire group of
50 subjects was a reduction of 9.1 pain days per month since the completion of the
experimental intervention.
Table II contains the same data. but broken down into those who continued to
comply with the intervention after 3 years, and those who did not continue to comply.
Compliance was determined from the answers to Question 2. Subjects who continued
to comply (N = 31) reported a reduction of 10.1 pain days per month; those who did not
continue to comply (N = 19). 7.5 pain days per month. There was a greater percentage
of noncompliant subjects with an increase in pain days, and the number of pain days
was greater. However, there was no statistically significant difference between the
compliance and noncompliance groups (Student's t test).
The baseline data for the 10 subjects who did not respond to the follow-up
questionnaire were compared with the baseline data for the 50 subjects who did
respond. The mean pain intensity for the nonresponders was 2.77; for the responders,
2.61. The number of pain days over 6 months for the non
r
esponders was 149; for the
responders, 144. There was no statistically significant difference in baseline data
between the two groups (Student's t test). Similarly, the original trial results for the
nonresponders were compared to the results for the responders. The reduction in pain
intensity for the nonresponders was 0.76: for the responders, 0.56. The reduction in the
number of pain days over 6 months for the nonresponders was 24.9: for the
responders, 20.6. There was no statistically significant difference in the results
between the responders and the nonresponders (Student's t test).
DISCUSSION
At the end of the original trial, 80% of the subjects said that they intended to
continue the restriction of bending activities in the early morning. After 3 years. 62%
reported that they continued to restrict bending activities in the early morning. Those
who did not continue
16 Snook, Webster, and McCorry
with the intervention cited reasons of increased stiffness or pain, inability to change their
morning routine, or strong beliefs in the value of the sham treatment (i.e., exercises).
Based upon the results of this follow-up study, subjects not only maintained the results
obtained during the original trial, but improved upon them. Table IIl illustrates subject
progress through the original trial and the
'
3-year follow-up. Upon entering the study, this
particular group of 50 subjects had reported a mean duration of pain of 17.28 years. The
average number of pain days per month was 24. Eighteen months later, at the end of the
experiment, the number of pain days per month was reduced to 19.7 (a reduction of 18%).
Three years later, subjects reported only 10.6 pain days per month, a reduction of 56% from
baseline data.
It is difficult to explain why some of the subjects in the noncompliance group did nearly
as well as subjects in the compliance group. Several possibilities exist.
1. The natural course of low back pain. Von Korff et
al. believe that the potential for
improvement of "chronic" back pain patients may be greater than suggested by
studies of pain clinic patients or persons who are work disabled (8).
2. Effectiveness of the sham treatment. Although the sham treatment was a series of
exercises found by Faas et al. to be ineffective in reducing low back pain (6). there is
the possibility that some subjects may have benefited from the exercises.
3. Partial compliance. Subjects were told that the first 2 h after rising were the most
important time of the day to protect and maintain a straight back. These instructions
may have led some subjects (whether consciously or unconsciously) to protect the
hack during the early morning, without considering it to be full compliance. For
example, one subject commented that she no longer complies with the intervention, but
she performs the sham treatment exercises at night rather than in the morning.
4. Cessation of compliance clue to successful revolution of low back pain. One subject
specifically stated this as a reason for noncompliance.
5. The placebo effect. Weinstein has suggested that the placebo effect can be very
significant—as high as 55–60% in treating pain (9).
It is interesting to note that 79% of those in the noncompliance group came from the
sham treatment (control) group. Furthermore, 32% of the noncompliance group commented that
they believed the exercises were the reason for their pain reduction. Many control group
subjects in the original trial were reluctant to give up the exercises when the crossover
occurred during Phase 2 of the trial. They were told that they could continue the exercises, but
only in the late afternoon or evening. Whether the exercises were somewhat effective, or
whether the subjects' strong beliefs in the exercises produced a placebo effect, is open to
speculation.
Reduction of Chronic, Nonspecific Low Back Pain—3-Year Follow-Up 17
The original trial was designed to control for placebo effects. Indeed, pain intensity and
pain days in the control group were reduced 6 and 2%. respectively, during Phasc I. This may
have been due to a placebo effect, to the natural course of the disorder, or to some effectiveness of
the sham treatment. The treatment group, on the other hand, experienced significant reductions
in pain intensity and pain days of 29 and 23%, respectively. After the partial crossover in Phase 2,
control group subjects received the experimental intervention (viz., instructions in the control of
early morning lumbar flexion). However, the control group did not perform as well as the
treatment group (19 and 10% reductions in pain intensity and pain days. respectively, from
baseline values). These results suggest that the order of presentation (i.e., sham treatment first,
or experimental treatment first) may have influenced the outcome.
The subjects' continued improvement during the 3-year follow-up was consistent with some of
the findings from the original trial. During Phase 2 of the trial, the treatment group subjects
continued the intervention for an additional 6 months. These subjects demonstrated additional
pain reduction during Phase 2 when compared with their results during Phase I.
Caution must be exercised when interpreting these results. Although the original experiment
was a randomized controlled trial, the follow-up study was not controlled. It cannot be
concluded with certainty that the control of lumbar flexion in the early morning was the only
reason for the reduced pain. However, when considering the long duration of pain experienced by
these subjects (17.28 years), and that 62% of subjects continue to restrict bending activities in
the early morning, it is reasonable to assume that lumbar flexion control in the early morning was
at least partially responsible for the positive results.
The results of this study provide an affirmative answer to the question of Adams et cal.
regarding clinical significance (3,4). The original trial concluded that the control of lumbar flexion
in the early morning is a form of self-care that can help develop a sense of control or mastery
over low hack pain, and thereby build confidence and improve outcome. The results also suggest
that therapists should not instruct patients with chronic or recur
r
ent low back pain to perform
morning exercises that involve lumbar flexion. The results of the follow-up study provide
continued support for the original conclusion, especially for the compliance group. However,
the improvement of some of the noncompliant subjects cannot be fully explained by this follow-
up study. Further research on the order of treatment presentations would help explain the
improvement of noncompliant subjects. Further research in health care settings is also necessary to
confirm the results of this experimental study.
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Spine 2000.25: 662-669.
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disc. Spine 2001; 26: 1223-1230.
3. Adams MA, Dolan P, Hutton WC. Diurnal variations in the stresses on the lumbar spine. Spine 1987; 12: 130-137.
4. Adams MA, Dolan P, Hutton WC, Porter RW. Diurnal changes in spinal mechanics and their clinical significance.
J Bone Joint Surg Br 1990; 72B: 266-270.
5. Snook SH, Webster BS, McGorry RW, Fogleman MT, McCann KB. The reduction of chronic nonspecific low back
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18 Snook,
W
ebster, and McGorr
y
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