Strengths and limitations
A high response rate, which is unusual for studies of GPs,19 along with little missing data on antibiotic prescribing (0.3%) are strengths of this study. GP registrar characteristics were reflective of the Australian GP registrar population overall,20 and their practices were located in major cities, inner and outer regional areas, and remote areas. The participating Regional Training Organisations train 43% of Australian GP registrars.20 That a large proportion of Australian registrars participated in the study, and their characteristics were similar to those of the wider registrar population, suggests generalisability to Australian specialist general practice vocational training.
A limitation is that contextual clinical details for the presenting conditions are not known, so it was not possible to judge how appropriate the prescription of antibiotics was for any individual problem/diagnosis; however, the finding that total prescribing is greatly in excess of benchmarks for all ARTIs other than URTI is robust because clinical judgement is implicit to the range of those benchmarks.18 A risk of misclassification bias and social desirability bias does exist, however, when a registrar does not accurately record an ARTI diagnosis because they prescribed antibiotics; the authors regard this risk as likely to be small — in ReCEnT, registrars record the broad range of their clinical activities over consecutive consultations (there is no focus on any single activity, including antibiotic prescribing).
The authors did not have data on whether patients filled the delayed prescriptions or actually took the dispensed antibiotics, nor did they have data on clinical outcomes; however, this is not considered a substantive limitation as the focus of the study was registrars’ prescribing behaviour. To put the findings into some context, however, it has been found in randomised controlled trials of delayed prescribing that 31% of delayed scripts will be filled (with delayed scripts provided at consultation being more likely to be filled than those to be collected later).5
Comparison with existing literature
In the study presented here, GP registrars used no prescribing substantially more often than established Australian GPs in McCullough et al’s modelling1 for acute bronchitis/bronchiolitis (32% versus 15%), otitis media (26% versus 11%), and sore throat (41% versus 6%) (Figure 1, Supplementary Table S1). For URTI, GP registrars prescribed within the benchmark specified by the European Surveillance of Antimicrobial Consumption disease-specific benchmarks,18 which have been validated for use in Australian general practice,21 but this was not the case for the other ARTIs reported here.
When prescribing antibiotics, it appears Australian GP registrars are using delayed prescribing more often than European GPs: in a multi-country study, European GPs used delayed prescribing for 12% of prescriptions written for lower respiratory tract infections/ARTIs with cough as the dominant symptom.9 This percentage is most closely comparable with acute bronchitis/bronchiolitis in the study presented here — in which registrars used delayed prescribing for 16% of prescriptions written. For all cases (including where no antibiotic was prescribed), European GPs used delayed prescribing in 6.3%,9 compared with 11% of bronchitis/bronchiolitis in the study presented here.
Prescribing antibiotics was more likely when there were markers of clinical concern, such as seeking information or assistance during the consultation or arranging specific follow-up. This suggests GP registrars may be addressing their diagnostic uncertainty regarding a more serious illness and the perceived consequences of not prescribing antibiotics. The authors have previously found that, when GP registrars seek help from their supervisor, they are significantly more likely to prescribe antibiotics for URTI and acute bronchitis22 — diagnoses for which authoritative Australian guidelines recommend not prescribing antibiotics.23 Data for this study do not include clinical information to ascertain how appropriate antibiotic prescription was in other ARTIs, but it is noted that established GPs prescribe substantially more antibiotics for ARTIs in Australia than GP registrars1 and also prescribe more than in similar medical systems in Europe and Canada.2 Consequently, one possibility is that GP registrars may use immediate prescribing to be consistent with a supervisor’s and/or a practice-wide approach to ARTIs; this is consistent with the authors’ findings of qualitative research in this area24 and may be supported by the finding of GP registrars being more likely to prescribe an antibiotic if they ask their supervisor for information or assistance.
Ordering imaging (for example, chest X-ray) can also be interpreted as a marker of clinical concern, but it is strongly associated with no prescribing. In Australia, GPs (including GP registrars) can order imaging, including a radiologist report, and expect it to be performed the same day. One interpretation of this association could relate to advice to confirm a possible pneumonia diagnosis with a chest X-ray,23 resulting in a delay in initiating antibiotics at first presentation; consequently, the GP registrar may diagnose an ARTI and investigate further before deciding whether it is pneumonia. The authors also found some evidence for immediate prescribing also being associated with imaging; this is consistent with the GP registrar, in some cases, addressing their diagnostic uncertainty by taking a pre-emptive approach and deciding to prescribe antibiotics for a more-severe ARTI, whether or not a subsequent chest X-ray demonstrates pneumonia.24
Delayed prescribing is associated with longer consultation duration; this may reflect more time being needed for complex or concerning presentations, with diagnostic uncertainty leading to the ‘safety net’ of delayed antibiotic prescribing. This is consistent with the authors’ qualitative findings in this area,24 but it may be that more time is needed to undertake an explanation of delayed prescribing rather than no prescribing.
The finding that with each additional problem/diagnosis dealt with in the consultation, delayed prescribing was increasingly less likely than both no prescribing and immediate prescribing could suggest that the GP registrar is choosing a strategy that requires less explanation and, consequently, less time in a busy consultation.
These associations with prescribing antibiotics — that is, markers of clinical concern, increased consultation duration, fewer problems/diagnoses managed per consultation — provide limited evidence that is congruent with qualitative findings. Some GP registrars use delayed prescribing, not only to address their own diagnostic uncertainty, but also to accommodate conflicting influences on prescribing for ARTIs such as: national guideline advice against use of antibiotics, desire to adhere to antimicrobial stewardship, knowledge that delayed prescribing reduces antibiotic consumption, both perceived and actual expectation from patients that antibiotics are necessary, and a supervisor approach or practice culture to prescribing for ARTIs.22,24
The associations of the individual respiratory infective illness classifications used in this study, when compared with URTI, showed immediate prescribing was more likely than delayed prescribing, and delayed prescribing was more likely than no prescribing. The findings regarding otitis media, sore throat, and sinusitis may partly reflect Australian guideline recommendations23 that antibiotics are indicated for these diagnoses in selected situations (and that delayed prescribing is an option in some circumstances). However, the associations of acute bronchitis (and the large effect sizes of these associations) cannot be reconciled with current Australian guideline recommendations that antibiotics are not indicated for acute bronchitis.23
