Objective To analyse the change of mortality rates (MRs) and their contributing medical factors among nursing home patients during the 2003 heat wave in France. Methods A retrospective observational study was conduced in all nursing homes of the Assistance-Publique-Hopitaux de Paris (AP-HP), the French largest public hospital group. All AP-HP nursing home patients (4403) who were institutionalized in May, 2003, were concerned. The MRs of patients between three periods (before, during and after the August 2003 heat wave period) were compared according to their demographic characteristics, level of dependence and medical condition. Results The MR increased from 2.2 per cent persons month (ppm) (1.9-2.4) before heat wave up to 9.2 ppm (8.0-10.4) during heat wave and back to 2.4 ppm (2.2-2.7) after heat wave. MRs before heat wave were higher among highly dependent patients compared to those less dependent [mortality rate ratio (MRR) = 2.66 (1.69-4.21)]. This difference disappeared during the heat wave [MRR = 1.28 (0.91-1.81)] and appeared again after heat wave [MRR = 2.21 (1.52-3.23)]. The same pattern was observed for several medical conditions, such as severe malnutrition or swallowing disorders. Conclusion These results suggest that medical care during heat wave has been directed towards more fragile patients, helping to limit deaths in this group. Less frail patients made the largest contribution to excess mortality during the heat wave. During extreme weather conditions, specific attention should be paid not only to frail persons, but to all the elderly community.
