Changes in self-reported health trajectories with focus on ageing in the Tromsø study

Abstract

Aim: We aim to describe factors that affect self-reported health (SRH) and to describe differences in trajectories in an ageing cohort according to comorbid diseases, mental health, physical condition, education, and physical activity. Methods: Prospective cohort study of a general population in Norway utilizing repeated surveys and physical examinations (1986-2008). We included 16 745 men and women aged 20-74 at baseline, living in Tromsø municipality. Average followed-up time was 11 years. Results: The steepest decline of SRH was in midlife and when passing life expectancy. SRH decreased differently over time for men and women. The most important factors determining SRH was mental health symptoms (31.6%), specific medical conditions (17.5%) and age (17.6%), which combined explained 45.2% of the variance. Medical conditions affected SRH dependent on when in life it occurred - e.g. cardiovascular diseases affected more at younger age while asthma and diabetes affected the elderly more. BMI above 27kg/m2 (-0.086, CI: -0.170, -0.002) was detrimental for SRH at all ages. Very lean subjects had a significantly larger negative effect with increasing age than all others. BMI < 18.5 kg/m2 (0.282 CI: 0.004, 0.560) developed into a negative difference late in life because SRH deteriorated rapidly with age in the lowest BMI group (-0.078 CI: -0.127, -0.028). Exercise levels depended on age; intensive training was beneficial at younger ages, but unfavourable at older ages. Intermediate training was most beneficial from age 63 and above. Higher levels of education benefitted SRH. Conclusion: Ageing is an independent factor influencing SRH. Disease or mental illness symptoms are associated with lower SRH whenever in life they occur. Variations in SRH trajectories suggest that low BMI and exercise levels become increasingly important especially as the population ages.