Factors affecting general practitioner charges and Medicare bulk-billing: results of a survey of Australians — erratum

In our study,1 we engaged the services of a third party online panel to recruit survey participants. Pre-existing information on private health insurance status, smoking status and exercise participation for those completing the survey was provided by the third party, who has now confirmed that the data initially labelled as “private health insurance” were actually “smoking” status. All other demographic information used in our analysis was collected directly from participants completing the online survey.

We initially reported a positive association between private health insurance and being bulk-billed (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.09–1.78). However, the discovery of this labelling error better explains the positive association we initially reported for those data; it is smokers who are more likely to be bulk-billed than non-smokers, not those with private health insurance being more likely to be bulk-billed than those without private health insurance. Retaining these data on smoking status in our model, and adding in the correct data for private health insurance status, we observe that those with private health insurance are less likely to be bulk-billed than those without it (OR, 0.63; 95% CI, 0.51–0.77). The remaining relationships between individuals’ characteristics and the likelihood of being bulked-billed are unchanged from those reported previously. The results from the updated multivariate logistic regression analysis are provided in the Box.

Box – Odds ratios for factors associated with bulk billing (n = 2467)

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Multivariate regression statistic Wald χ² = 234.63 (P = < 0.001). Bars represent 95% confidence intervals (CIs). For each category, except age, the base factor appears without a 95% CI and straddles the line at 1. The number of respondents included was reduced by ten due to six missing observations for age and four missing observations for concession card status. * P = < 0.05 compared with the base factor.