Mortality among the working age population receiving incapacity benefits in New Zealand, 1981-2004.

Like many OECD countries New Zealand has experienced a large increase in the number of working-age people receiving incapacity benefits in the last 3 decades, despite apparent improvements in population health. This paper examines trends in mortality rates of people receiving sickness benefit or invalid's benefit (SBIB) between 1981 and 2004 using repeated cohort studies (linking the 1981, 1986, 1991, 1996, and 2001 censuses to mortality data). Mortality rates, standardised for age and ethnicity, were calculated for each census cohort for 25-64 year olds by benefit receipt status. Standardised rate differences and rate ratios and 95% confidence intervals were calculated to measure disparities on both absolute and relative scales. Between 1981 and 2004 overall SBIB receipt increased from 2% to 5% of the working age population. Mortality rates were at least three times higher in the SBIB than the non-SBIB group at all points in time for men and women. Mortality rates declined in all groups, for example in men receiving SBIB, mortality decreased from 2354/100,000 in the 1981-84 cohort to 1371/100,000 in the 2001-04 cohort. Absolute inequalities between SBIB and non-SBIB declined in both men and women (for example in women standardised rate differences decreased from 954/100,000 to 688/100,000) but relative inequalities remained largely stable (for example in men the risk ratio increased from 4.27 to 4.54). Mortality rates declined more in sickness benefit than invalid's benefit recipients. The substantial expansion of SBIB receipt in New Zealand has not been accompanied by any reduction in the excess mortality risk experienced by SBIB recipients. These findings are likely to reflect the changing nature of the economy, labour force and disability experience in New Zealand.