The Ottawa ankle rules for the use of diagnostic X-ray in after hours medical centres in New Zealand.

AIMS

The aims of this study were to measure baseline use of Ottawa ankle rules (OAR), validate the OAR and, if appropriate, explore the impact of implementing the Rules on X-ray rates in a primary care, after hours medical centre setting.

METHODS

General practitioners (GPs) were surveyed to find their awareness of ankle injury guidelines. Data concerning diagnosis and X-ray utilisation were collected prospectively for patients presenting with ankle injuries to two after hours medical centres. The OAR were applied retrospectively, and the sensitivity and specificity of the OAR were compared with GPs clinical judgement in ordering X-rays. The outcome measures were X-ray utilisation and diagnosis of fracture.

RESULTS

Awareness of the OAR was low. The sensitivity of the OAR for diagnosis of fractures was 100% (95% CI: 75.3 - 100) and the specificity was 47% (95% CI: 40.5 - 54.5). The sensitivity of GPs clinical judgement was 100% (95% CI: 75.3 - 100) and the specificity was 37% (95% CI: 30.2 - 44.2). Implementing the OAR would reduce X-ray utilisation by 16% (95% CI: approx 10.8 - 21.3).

CONCLUSIONS

The OAR are valid in a New Zealand primary care setting. Further implementation of the rules would result in some reduction of X-rays ordered for ankle injuries, but less than the reduction found in previous studies.