Association between daily maximum temperature and immediate-to-delayed gout flare hospitalisations: a population-level time series study in metropolitan Perth, Australia.

BACKGROUND

Ambient temperature may alter the risk of gout flare. We assessed the association between daily maximum temperature on the immediate-to-delayed (lag) gout flare hospitalisations at the population-level.

METHODS

Data were extracted from the Western Australian Hospital Morbidity Data Collection for this time series study for metropolitan Perth (Australia) from 1980-2014, with meteorological data obtained from the Scientific Information for Land Owners dataset. We examined the association (relative risk [RR] and 95% confidence intervals [CI]) between gout flare hospitalisations, daily maximum temperature and lag days since exposure using quasi-Poisson regression and the distributed lag non-linear model.

RESULTS

Average daily maximum temperature was 24°C (5th percentile=17°C; 95th percentile=36°C). There were 6.2 and 6.8 gout flare hospitalisations per 1,000,000 population, from lag day 0 to lag day 21 following exposure to maximum temperatures of 17°C and 36°C, respectively. Risk of gout flare hospitalisations (reference=24°C) with maximum temperature was modified by sex and age. Males aged ≥75 years had higher risk of gout flare hospitalisations following hotter days (36°C), beginning immediately on lag day 0 (RR=1.39; 95% CI: 1.02-1.88) and from lag day 7 (RR=1.11; 95% CI: 1.01-1.21) to lag day 10 after colder days (≤15°C). Females aged ≥75 years had higher risk from lag day 3 (RR=1.12; 95% CI: 1.02-1.23) to lag day 4 after a 35°C day. Males aged <75 years had higher risks from lag day 6 (RR=1.06; 95% CI: 1.01-1.12) to lag day 8 after 35°C days but lower risk from lag day 7 (RR=0.96: 95% CI: 0.92-0.99) to lag day 8 following colder days (17°C).

CONCLUSION

Our study shows associations between extreme temperatures, both hot and cold, and immediate-to-delayed gout flare hospitalisations. Our findings will inform and guide public health measures and health system preparedness during the impending extremes of temperature with particular attention to older people.