Mika Kivimäki’s research while affiliated with Finnish Institute of Occupational Health and other places

Self-rated health is a major indicator of an individual’s overall health status, but its development during midlife to old age, as well as influence of sociodemographic and work-related factors on it, are poorly understood. We used longitudinal individual-level data to examine trajectories of self-rated health and their determinants in 38,163 participants (median age 50 (range 36–66) years at baseline) of the English Longitudinal Study of Ageing, the Finnish Longitudinal Study on Aging Municipal Employees, and the French GAZ and ELectricité study from Europe and the Health and Retirement Study from the US. A group-based latent trajectory analysis showed that self-rated health was constantly good for over half of the participants, constantly suboptimal for about 11–21%, and it was changing, either improving or declining, for the rest. Pooled evidence suggests that being single (summary odds ratio 1.20, 95% confidence interval 1.07–1.35), medium educational attainment (1.26, 1.16–1.37), medium occupational class (1.22, 1.10–1.34), and exposure to high physical job demands (1.18, 1.08–1.29) were associated with declining self-rated health. Suboptimal self-rated health was more prevalent among those in low occupational class (1.81, 1.56–2.10), and those who experienced high physical job demands (1.52, 1.33–1.74). In these European and US populations, 23–40% of people experienced suboptimal or declining health trajectories. In conclusion, large variation in development of self-rated health from midlife to old age was observed and it was partly determined by sociodemographic and work-related factors.

Background Regular physical activity is recommended for all aged 5 years and older, but the health benefits gained might differ across population subgroups. The aim of this study was to examine these benefits in terms of years lived free from major non-communicable diseases in subgroups with varying levels of risk factors. Methods Our analysis was based on a multicohort study of initially healthy European adults from the IPD-Work Consortium and initially healthy participants from the UK Biobank study. Self-reported leisure-time physical activity levels at baseline (1986–2010) were categorised as low (no or very little), intermediate (between low and recommended levels), and WHO-recommended (≥2·5 h of moderate or ≥1·25 h of vigorous physical activity per week). We divided the study population into 36 overlapping subgroups based on socioeconomic factors, lifestyle, and mental health at baseline, and assessed disease-free years between ages 40 years and 75 years for both the overall population and subgroups, accounting for coronary heart disease, stroke, type 2 diabetes, cancer, asthma, and chronic obstructive pulmonary disease. Findings 14 IPD-Work studies were assessed and six studies were excluded due to missing outcome data and unavailable data for pooling, resulting in the inclusion of eight studies with 124 909 participants. After the exclusion of 7685 participants due to prevalent diseases and 9265 due to missing data, the sample consisted of 107 959 initially healthy European adults (63 567 [58·9%] females and 44 392 [41·1%] males) from the IPD-Work consortium. For the UK Biobank sample, 9 238 453 million individuals were invited, 8 736 094 (94·6%) were non-respondents, and 502 359 participated in the baseline examination. After the exclusion of 73 460 participants, 428 899 participants had data on at least one measure of physical activity. 236 258 (55·1%) were female and 192 641 (44·9%) were male. During 1·6 million person-years at risk, 21 231 IPD-Work participants developed a non-communicable disease, while 101 319 UK Biobank participants developed a non-communicable disease over 4·8 million person-years at risk. Compared with individuals with low physical activity, those meeting the recommended physical activity levels during leisure-time gained an additional 1·1 (95% CI 1·0–1·2) to 2·0 (1·7–2·3) disease-free years, depending on sex and study. In males from the IPD-Work and UK Biobank cohorts, greater gains in disease-free years were observed in current smokers (2·4 [95% CI 2·1–2·8]) versus never smokers (0·7 [0·5–0·9]); those with low education (1·4 [1·1–1·7]) versus high education (0·8 [0·7–1·0]); low socioeconomic status (1·7 [1·5–2·0]) versus high socioeconomic status (0·9 [0·7–1·1]); and those with (1·6 [1·3–1·9]) versus without depressive symptoms (1·0 [0·9–1·1]; p value range <0·0001–0·0008). Similar differences were seen in women for smoking (2·3 [95% CI 1·9–2·7] vs 0·9 [0·7–1·1]), socioeconomic status (1·7 [1·4–2·0] vs 0·8 [0·5–1·0]), depressive symptoms (1·4 [1·1–1·7] vs 1·0 [0·9–1·1]), and for heavy drinkers compared with moderate drinkers (1·4 [1·1–1·6] vs 0·9 [0·7–1·1]; p value range <0·0001–0·010). No differences in physical activity-related health gains were observed between risk groups and non-risk groups by BMI, history of depression, and, in men, alcohol use (p value range 0·11–0·86). Interpretation In addition to confirming the association between leisure-time physical activity and increased disease-free years across population subgroups, our findings show that these health benefits are often more pronounced among individuals with pre-existing health risks or disadvantaged backgrounds than in those with more favourable risk factor profiles. This suggests that enhancing population-wide physical activity initiatives could help reduce health disparities, while incorporating physical activity into targeted strategies addressing social disadvantage, unhealthy lifestyles, and depression might enhance their effectiveness. Funding Wellcome Trust, UK Medical Research Council, US National Institute on Aging, and Research Council of Finland.

Background The COVID-19 pandemic was a significant health risk and resulted in increased sickness absence during the pandemic. This study examines whether a history of COVID-19 infection is associated with a higher risk of subsequent sickness absence. Methods In this prospective cohort study, 32,124 public sector employees responded to a survey on COVID-19 infection and lifestyle factors in 2020 and were linked to sickness absence records before (2019) and after (2021–2022) the survey. Study outcome was annual sickness absence defined as the total number of sickness absence days and the number of short sickness absence spells (< 10 days) and long sickness absence spells (10–365 days). We used negative binomial regression adjusting for sex, age, employment characteristics, body mass index, health behaviors in 2020 and sickness absence in 2019. We examined differences in sickness absence between socioeconomic statuses (SES), measured by occupational titles from employers’ records. Results A self-reported COVID-19 infection in 2020 was associated with higher subsequent risk of sickness absence in 2021: Adjusted Incidence Rate Ratio (IRR) compared to those not reporting COVID-19 was 1.23, 95% confidence interval (CI) 1.10–1.37 for sickness absence days, 1.29, 1.20–1.38 for short sickness absence spells and 1.20, 1.04–1.37 for long spells. The association was strongest in employees with intermediate SES: 1.45, 1.20–1.77 days, 1.42, 1.26–1.61 short spells, and 1.30, 1.03–1.64 long spells. For employees with low and high SES, an association was observed only for short spells. Conclusions Employees who reported contracting first-wave COVID-19 infection had higher rates of sickness absence in the following year. This excess risk was most consistently observed in employees with intermediate socioeconomic status (e.g. office workers, registered nurses, and social workers).

This study investigated the associations between personality traits of the Five Factor Model and cardiovascular mortality, with a specific focus on whether pre-existing cardiovascular conditions modified these associations. We used data from 43,027 participants across five cohort studies: Health and Retirement Study (HRS); Wisconsin Longitudinal Study (WLS); National Social Life, Health, and Aging Project (NSHAP); Midlife in the United States (MIDUS); Household, Income, and Labour Dynamics in Australia (HILDA) with a mean age 55.9 years and 6493 individuals with pre-existing cardiovascular disease. We conducted meta-analyses examining conscientiousness, emotional stability, agreeableness, openness to experience, and extraversion in relation to mortality due to coronary heart disease and stroke. During a mean follow-up of 12.1 years, 1620 participants died from coronary heart disease and 454 from stroke. Lower conscientiousness was associated with higher mortality risk from both coronary heart disease (hazard ratio per 1SD = 0.82, 95%CI = 0.75–0.90) and stroke (HR = 0.84, CI = 0.72–0.99). Lower emotional stability predicted increased coronary heart disease mortality (HR = 0.91, CI = 0.85–0.97). The association between conscientiousness and cardiovascular mortality did not differ between individuals with or without baseline cardiovascular conditions. In addition, adjustments for health behaviors and other covariates only slightly attenuated this association. Other personality traits were not associated with cardiovascular disease mortality. Our findings highlight the role of low conscientiousness, and to a lesser extent low emotional stability, in the development and progression of fatal cardiovascular disease through pathways that may extend beyond established health behaviors.

Employee turnover is a challenge for public sector employers. In this study, we used machine learning to develop and validate models to predict actualized turnover of Finnish public sector workers. The development cohort data (N=52 291) included 158 variables from 2018. We defined overall turnover (regardless of reason) and net turnover (excluding workers in retirement age) through eligibility to a follow-up survey in 2020. The validation cohort included 9030 hospital workers who responded to survey in 2017, with turnover assessed in 2019. Area under the curve (AUC) value was 0.75 (95% CI: 0.74-0.76) for overall turnover and 0.75 (95% CI 0.73-0.76) for net turnover. The validation yielded similar AUC values. Key predictors of turnover were younger age, shorter job tenure, and turnover intentions totaling over 70% of the net gain. Work-related exposures, of which low threat of lay-off and satisfaction with challenges at work were most important, had considerably lower predictive power (about 1% each). These results may offer insights for public sector employers in their efforts to reduce employee turnover.

Infections have been associated with the incidence of Alzheimer disease and related dementias, but the mechanisms responsible for these associations remain unclear. Using a multicohort approach, we found that influenza, viral, respiratory, and skin and subcutaneous infections were associated with increased long-term dementia risk. These infections were also associated with region-specific brain volume loss, most commonly in the temporal lobe. We identified 260 out of 942 immunologically relevant proteins in plasma that were differentially expressed in individuals with an infection history. Of the infection-related proteins, 35 predicted volumetric changes in brain regions vulnerable to infection-specific atrophy. Several of these proteins, including PIK3CG, PACSIN2, and PRKCB, were related to cognitive decline and plasma biomarkers of dementia (Aβ42/40, GFAP, NfL, pTau-181). Genetic variants that influenced expression of immunologically relevant infection-related proteins, including ITGB6 and TLR5, predicted brain volume loss. Our findings support the role of infections in dementia risk and identify molecular mediators by which infections may contribute to neurodegeneration.

Background While individuals who were separated from their biological family and placed into the care of the state during childhood (out-of-home care) are more prone to developing selected adverse health problems in adulthood, their risk of cardiovascular disease is uncertain. Our aim was to explore this association by pooling published and unpublished results from prospective cohort studies. Methods We used two approaches to identifying relevant data on childhood care and adult cardiovascular disease (PROSPERO registration CRD42021254665). First, to locate published studies, we searched PubMed (Medline) until November 2023. Second, with the objective of identifying unpublished studies with the potential to address the present research question, we scrutinised retrieved reviews on childhood out-of-home care and other adult health outcomes. Included studies were required to satisfy three criteria: a cohort study in which the assessment of care was made prospectively pre-adulthood (in the avoidance of recall bias); data on an unexposed comparator group were available (for the computation of relative risk); and a diagnosis of adult cardiovascular disease events (coronary heart disease, stroke, or their combination) had been made (as opposed to risk factors only). Collaborating investigators provided study-specific estimates which were aggregated using random-effects meta-analysis. The Newcastle-Ottawa Scale was used to assess individual study quality. Findings Twelve studies (2 published, 10 unpublished) met the inclusion criteria, and investigators from nine provided viable results, including updated analyses of the published studies. Studies comprised 611,601 individuals (301,129 women) from the US, UK, Sweden, Finland, and Australia. Five of the nine studies were judged to be of higher methodological quality. Relative to the unexposed, individuals with a care placement during childhood had a 51% greater risk of cardiovascular disease in adulthood (summary rate ratio after age- and sex-adjustment [95% confidence interval]: 1.51 [1.22, 1.86]; range of study-specific estimates: 1.07 to 2.06; I² = 69%, p = 0.001). This association was attenuated but persisted after adjustment for socioeconomic status in childhood (8 studies; 1.41 [1.15, 1.72]) and adulthood (9 studies, 1.29 [1.11, 1.51]). Interpretation Our findings show that individuals with experience of out-of-home care in childhood have a moderately raised risk of cardiovascular disease in adulthood. Funding 10.13039/501100000265Medical Research Council; 10.13039/100000049National Institute on Aging; 10.13039/100010269Wellcome Trust.