Self-reported visual impairment, physical activity and all-cause mortality: The HUNT Study

Aims: To examine the associations of self-reported visual impairment and physical activity (PA) with all-cause mortality. Methods: This prospective cohort study included 65,236 Norwegians aged 20 years who had participated in the Nord-TrOndelag Health Study (HUNT2, 1995-1997). Of these participants, 11,074 (17.0%) had self-reported visual impairment (SRVI). The participants' data were linked to Norway's Cause of Death Registry and followed throughout 2012. Hazard ratios and 95% confidence intervals (CI) were assessed using Cox regression analyses with age as the time-scale. The Cox models were fitted for restricted age groups (<60, 60-84, 85 years). Results: After a mean follow-up of 14.5 years, 13,549 deaths were identified. Compared with adults with self-reported no visual impairment, the multivariable hazard ratios among adults with SRVI were 2.47 (95% CI 1.94-3.13) in those aged <60 years, 1.22 (95% CI 1.13-1.33) in those aged 60-84 years and 1.05 (95% CI 0.96-1.15) in those aged 85 years. The strength of the associations remained similar or stronger after additionally controlling for PA. When examining the joint associations, the all-cause mortality risk of SRVI was higher for those who reported no PA than for those who reported weekly hours of PA. We found a large, positive departure from additivity in adults aged <60 years, whereas the departure from additivity was small for the other age groups. Conclusions: Adults with SRVI reporting no PA were associated with an increased all-cause mortality risk. The associations attenuated with age.