Background: The 2019/20 bushfire season was one of the worst in Australian history with widespread dispersal of smoke across the country. The impact of bushfire on hospital presentations has been previously described but there is limited data on its impact on primary care.
Method: This study compared condition-specific clinical encounter rates before and during the bushfire season, on bushfire smoke affected and non-affected days, among patients visiting one of 258 general practices participating in MedicineInsight (a national general practice database) between September 2018 and January 2020. A bushfire smoke affected day was defined as one with a 24?hour mean particulate matter level that exceeded the 95th percentile of historical daily mean values and was ?25 mcg/m3. The analysis controlled for geographical location, day of the week and underlying trends in condition encounter rates from the previous year to the bushfire affected year.
Results: When comparing encounter data from a bushfire affected day to the corresponding date in the previous year, there were 2 extra asthma encounters per 1,000 encounters (a 24% increase) on bushfire smoke affected days. In contrast, presentations for upper respiratory tract infections fell. There was a non-significant trend towards increased presentations of stroke and heart attacks. There were no significant differences in encounter rates for post-traumatic stress disorder (although this was significant in unadjusted analyses), depression or anxiety disorders.
Discussion: As seen in studies using hospital data, the number of patients presenting with asthma increased on bushfire affected days. The potential effect of bushfire smoke on encounters for post-traumatic stress disorder, heart attacks and stroke requires further research.
Implications for practice: On days which are affected by bushfires, there are significant differences in presentations to general practice as previously demonstrated in hospital settings. In periods of bushfire practices may need to be prepared for such changes.