Syndromic surveillance use to detect the early effects of heat-waves: an analysis of NHS direct data in England.

OBJECTIVE

To investigate the effects of high ambient temperatures, including the summer 2003 heat-episode, on NHS Direct usage and its suitability as a surveillance tool in heat health warning systems.

METHODS

Analyses of data on calls to NHS Direct in English Regions in the period Dec 2001-May 2004. Outcomes were daily rates of all symptomatic calls, and daily proportion of calls for selected causes (fever, vomiting, difficulty breathing, heat/sun-stroke)

RESULTS

Total calls were moderately increased as environmental temperature increased; this effect was greatest in calls for young children and for fever. Total calls were moderately elevated during two summer heat episodes in 2003: calls specifically for heat/sun stroke increased acutely in response to these episodes. No association was apparent between environmental temperature and proportion of calls for vomiting and difficulty breathing.

CONCLUSIONS

Calls to NHS Direct are sensitive to daily temperatures and extreme weather. NHS Direct is timely and has great potential in health surveillance. Calls for heat- and sun-stroke are now routinely monitored as part of the UK Heat-wave plan