Prevalences and disabling impacts of disease.

Abbreviations: CNSLD = chronic non-specific lung disease; DM = diabetes mellitus; PVD = peripheral vascular disease (upper extremity excluded).5 year age groups were used to calculate the disabling impact of diseases and the prevalence of disability by cause (table 3). To summarize and as is shown in the table, disabling impacts were also calculated using three age-aggregated groups (55–64.9, 65–79.9, > = 80). ‘Background’, representing presence of disability irrespective of disease presence, is preferably modelled according to 5 year age groups and could therefore not be shown in the table.The disabling impact represents the rate of disability from a specific cause given that the disease is present. Adding these specific disability rates for the diseases present and the background rate of disability (by age and gender) gives the total disability rate for a specific exposure group. The proportion of the cause-specific rate in total rate is used to divide the probability of disability in this group by cause. For example, for males aged 75–79 with PVD and arthritis, adding the background rate (0.03), the rate for PVD (0.17), and the rate for arthritis (0.07) yields a total disability rate of 0.27 and a total probability of disability of 0.24 (1 − exp(−0.27) = 0.24). The probability of disability from background in this group is 0.03 (0.03/0.27 * 0.24), that of PVD is 0.15 (0.17/0.27 * 0.24), and that of arthritis is 0.06 (0.07/0.27 * 0.24).The disabling impact for males and females was significantly different (P