Long-term Changes in Depressive Symptoms and Estimated Cardiorespiratory Fitness and Risk of All-Cause Mortality: The Nord-Trøndelag Health Study

Abstract

Objective: To assess the independent and combined associations of long-term changes in depressive symptoms (DSs) and estimated cardiorespiratory fitness (eCRF) with all-cause mortality.

Participants and methods: This is a longitudinal cohort study of 15,217 middle-aged and older individuals attending both the second (from August 15, 1995, through June 18, 1997) and third (from October 3, 2006, through June 25, 2008) health surveys of the Nord-Trøndelag Health Study, Norway, and followed until December 31, 2014. Depressive symptoms were estimated using the validated Hospital Anxiety and Depression Scale, and a validated nonexercise model estimated eCRF. Hazard ratios (HRs) were computed using Cox regression. All-cause mortality was ascertained using the Norwegian Cause of Death Registry.

Results: The mean age was 63.3±8.9 years, and 7932 (52.1%) were women. During the follow-up period of 7.1±1.1 years, 1157 participants (7.6%) died. Multivariable-adjusted analyses revealed that persistently low DSs were independently associated with a 28% risk reduction of all-cause mortality (HR, 0.72; 95% CI, 0.56-0.92; P=.008) as compared with persistently high DSs. Persistently high eCRF independently predicted a 26% lower risk of death (HR, 0.76; 95% CI, 0.66-0.88; P<.001) relative to low eCRF. Analyses of changes in DSs and eCRF revealed that persistently high eCRF combined with decreased or persistently low DSs decreased mortality risk by 49% (HR, 0.51; 95% CI, 0.28-0.91; P=.02) and 47% (HR, 0.53; 95% CI, 0.37-0.76, P=.001), respectively.

Conclusion: Maintaining low DSs and high eCRF was independently associated with a lower risk of all-cause mortality. The lowest mortality risk was observed for persistently high eCRF combined with decreased or persistently low DSs. These results emphasize the effect of preventing DSs and maintaining high CRF on long-term mortality risk, which is potentially important for long-term population health.