Risk and rate advancement periods of total hip replacement due to primary osteoarthritis in relation to cumulative physical workload
Scandinavian Journal of Work, Environment and Health
Risk and rate advancement periods of total hip replacement due to primary osteoarthritis in relation to cumulative physical workload by Rubak TS, Svendsen SW, Søballe K, Frost P This is the first longitudinal study examining the risk and timing of total hip replacement (THR) due to primary osteoarthritis in relation to independently assessed lifelong cumulative physical workload at a population level. Among men, the most highly exposed group had an odds ratio of 1.3, and in this group, THR was
... his group, THR was performed 3.4 years earlier in life. Affiliation: Rubak TS, Svendsen SW, Søballe K, Frost P. Risk and rate advancement periods of total hip replacement due to primary osteoarthritis in relation to cumulative physical workload. Scand J Work Environ Health. 2013;39 (5) :486-494. doi:10.5271/sjweh.3365 Objectives This study aims to (i) evaluate relative risks, excess fraction of cases, and rate advancement periods for total hip replacement (THR) due to primary osteoarthritis in relation to lifelong cumulative physical workload and (ii) describe temporal trends in the proportion employed in the most highly exposed industries from 1986-2006. Methods In a cohort study of the Danish working population, we assessed cumulative physical workload by combining year-by-year register information on employment industry with an industry exposure matrix that provided point scores (0-2) of physical workload. Cumulative physical workload was expressed as point-years corresponding to the pack-year concept of smoking. We retrieved register information on first-time THR during 1996-2006 and used a logistic regression technique to fit discrete time hazards models adjusting for age and other factors. We calculated excess fraction of cases and rate advancement periods. Results Total numbers of point-years ranged from 0-86. For men, an exposure-response relation was observed reaching an odds ratio of 1.33 [95% confidence interval (95% CI) 1.17-1.53] for the highest exposure category (35-86 point-years) compared to 0 point-years. The excess fraction of cases was 18%, and THR took place up to 3.4 years earlier with increasing exposure. For women, no exposure-response relation was found. Conclusions At the population level, cumulative physical workload increased the risk of THR among men, with surgery being performed slightly earlier in life. The proportion employed in the most highly exposed industries remained constant.