ORIGINAL PAPER Risk factors for deaths during the 2009 heat wave in Adelaide, Australia: a matched case-control study Ying Zhang 1 & Monika Nitschke 2 & Antoinette Krackowizer 3 & Keith Dear 4 & Dino Pisaniello 3 & Philip Weinstein 5 & Graeme Tucker 2 & Sepehr Shakib 6 & Peng Bi 3 Received: 15 May 2015 /Revised: 18 March 2016 /Accepted: 8 May 2016 # ISB 2016 Abstract The extreme heat wave in Australia in 2009 result- ed in significantly increased number of daily deaths. The cir- cumstances that lead to deaths during extreme heat have not been explored before in Australia. This study aims to identify the individual and community risk factors for deaths during this extreme heat wave in Adelaide. A matched case-control study was conducted. Cases were those who died in the Adelaide metropolitan area during the heat wave period. For each case, two community controls were randomly selected, matched by age and gender. Face-to-face or telephone inter- views were conducted to collect data of demographic informa- tion, living environment, social support, health status and be- havioural changes during the heat wave. Descriptive analysis, as well as simple and multiple conditional logistic regressions were performed. In total, 82 deaths and 164 matched commu- nity controls were included in the analysis, with a median age of 77.5 (range 26.6–100.7). The multiple logistic regression model indicated that, compared with controls, the risk of death during the heat wave was significantly increased for people living alone (AOR = 42.31, 95 % CI 2.3, 792.8) or having existing chronic heart disease (AOR = 22.4, 95 % CI 1.7, 303.0). In addition, having air conditioning in bedrooms (AOR = 0.004, 95 % CI 0.00006, 0.28) and participating in social activities more than once a week (AOR = 0.011, 95 % CI 0.0004, 0.29) indicated significant protective effects. We have identified factors that could significantly impact on the likeli- hood of deaths during heat waves. Our findings could assist in the development of future intervention programs and policies to reduce mortality associated with a warmer climate. Keywords Heat wave . Risk factors . Mortality . Comorbidity . Case-control Introduction An increasing number of extreme heat events have been ob- served globally over the last decades and it is very likely that extreme heat events will occur more often and last longer in the future (IPCC 2013). Australia experienced very hot sum- mers in recent years culminating in the 2009 heat wave, which led to record-breaking prolonged high temperatures (Australian Bureau of Meteorology 2014). The increased death toll during heat waves has attracted worldwide attention and is described in a number of studies. For example, more than 70,000 excess deaths were attributed to the 2003 heat wave in Europe (Vandentorren et al. 2006). The 2009 Australia heat wave was related to a 62 % increase in mortality in Victoria and a 9.5 % increase in mortality in Adelaide (Nitschke et al. 2011). Our health impact studies in Adelaide show that heat waves can affect various vulnerable * Ying Zhang ying.zhang@sydney.edu.au * Peng Bi peng.bi@adelaide.edu.au 1 School of Public Health, China Studies Centre, University of Sydney, Sydney, NSW, Australia 2 South Australian Department for Health and Ageing (DHA), Adelaide, South Australia, Australia 3 School of Population Health, University of Adelaide, Adelaide, South Australia, Australia 4 Global Health Institute, Duke University and Duke Kunshan University, Kunshan, China 5 School of Biological Sciences, University of Adelaide, Adelaide, Australia 6 Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, Australia Int J Biometeorol DOI 10.1007/s00484-016-1189-9