Opioid prescribing in Australian general practice

lob an ch G al concern about the prescribing of opioid algesic medications (particularly oxycodone) for ronic pain is growing. In this Journal in September 2011, Roxburgh and colleagues examined the rise of oxycodone and morphine prescribing and the harm associated with opioid use.1 In the accompanying editorial, Hall and Farrell argued that this suggests that most prescribing of opioids was for chronic non-malignant pain.2 We tested this assertion using general practitioner prescribing data linked to the problem under management, and examined the characteristics of the GPs who prescribed opioids and the patients who received these prescriptions. We analysed data from the Bettering the Evaluation and Care of Health (BEACH) program (detailed methods are described elsewhere3). For the period April 2010 to March 2011, we examined encounters at which opioids were either prescribed or supplied directly to patients. We then measured changes in opioid and oxycodone prescribing rates over the past decade and extrapolated these results to all Medicare GP service items claimed nationally.4 While Roxburgh and colleagues1 reported dispensing rates as measured by the Pharmaceutical Benefits Scheme (PBS), BEACH data measure GP prescription and supply actions. Using the international Anatomical Therapeutic Chemical classification,5 we defined opioids as “N02A” and oxycodone as “N02AA05”. We determined the statistical significance of differences by non-overlapping 95% CIs. In the 2010–11 BEACH data year, at least one opioid was prescribed or supplied at 4666 of the 95 839 encounters (4.9%) recorded from 892 GPs (93.1% of the 958 GPs who participated in that year). There were a total of 5350 opioids prescribed (5237; 97.9%) or supplied (113; 2.1%) by the GP at the 4666 encounters. From this point, we shall refer to them all as being prescribed. Compared with encounters at which no opioids were recorded, those at which an opioid was prescribed were four times more likely to be claimable through workers compensation (6.8%; 95% CI, 5.7%– 7.8% v 1.7%; 95% CI, 1.5%–1.9%), and more likely to be long or prolonged consultations (10.0%; 95% CI, 8.8%– 11.2% v 7.8%, 95% CI, 7.2%–8.4%). Opioids were prescribed at a rate of 3.7 per 100 problems managed, accounting for 5.8% of all medications prescribed or supplied by participating GPs. There was no significant difference in opioid prescribing rates for male and female patients. Opioid prescribing was rare for young patients, rose significantly for patients aged 25–44 years, peaked among 45–64-year-old patients and stayed almost as high in older age groups. Opioid prescribing was significantly less for patients new to the practice, possibly because of their younger age (results not shown) or GP reluctance to prescribe opioids at an initial consultation (Box 1). Commonwealth Health Care Card holders had a significantly higher rate of opioid prescribing than other patients; this rate was even higher than for patients aged 65 years and older, suggesting that age was not the only contributing factor. While the prescribing rate for opioids did not differ with the age group of the GP, male GPs prescribed significantly more opioids per 100 encounters than did females (Box 2), adding to previous research evidence showing that female GPs prescribe fewer medications than males.6 Christopher M Harrison BPsych(Hons), MSocHlth, Senior Analyst