The impacts of withdrawal and replacement of general practitioner services on aeromedical service trends: a 13-year interrupted time-series study in Tennant Creek, Northern Territory

BACKGROUND: The Royal Flying Doctor Service (RFDS) provides aeromedical care to patients during fixed-wing transport over vast distances to healthcare unavailable in rural or remote communities. This study examined the relationship between changes in local accessibility to primary healthcare services and rates of aeromedical service use over time. METHODS: This was a 13-year interrupted time-series study (1999–2012) in Tennant Creek, Northern Territory. Quarterly aeromedical service use for primary care sensitive conditions were calculated and exposure to general practice (GP) services was characterised over time with events modelled as intervention variables: (a) GP service withdrawal (Nov-2004); and (b) GP service replacement (Dec-2006). Intervention effects were estimated using PROC ARIMA in SAS after examination of the time-series structure. RESULTS: GP withdrawal resulted in an immediate and sustained doubling in quarterly aeromedical service use (+11.8 services per quarter) and GP service replacement had no significant effect. DISCUSSION: Large and immediate increases in aeromedical service use result from the loss of local GPservices yet, in this case, replacement with a new GP service, 2-years hence, did not ameliorate that effect after six years. CONCLUSIONS: These findings demonstrate the immediate impact of GP-service loss on the rates ofaeromedical transfer of patients from this remote community and lend caution to expectations about thetimeline over which newly implemented primary health care services in such contexts can mitigate the impact of such a loss.