Utilising the epidemiologic triad in analysing quality improvement data: antibiotic use for respiratory infections as a case example.

Background: Quality improvement investigators working in field settings, who typically are not trained in epidemiological methods, may not consider all three elements of the epidemiologic triad (person, place and time) when planning their projects.

Aim: To demonstrate how the epidemiological triad can guide analysis for quality assessment. Predictors of antibiotic use in primary care were analysed to illustrate the approach.

Methods: This study was a secondary analysis of data previously collected from medical records and a provider survey. A convenience sample of 467 family medicine patients treated in two clinic sites for acute respiratory tract infections was analysed by locating quality variation in person, place and time. Independent variables included patient age, date of clinic visit, and clinic site. The outcome measure was antibiotic prescription (yes or no).

Results: Antibiotics were prescribed for 69.2% of patients in the sample. Age group was not related to antibiotic prescribing. Prescription was related to time (P = 0.0344) and clinic site (P = 0.0001) in univariate tests. However, only site was independently related to antibiotic prescription (odds ratio = 0.47, confidence interval = 0.30 to 0.73, P = 0.0008).

Conclusion: The epidemiological triad assisted in guiding further post hoc analysis of predictors of antibiotic prescriptions. Further investigations of this quality indicator can be directed at exploring site differences and testing interventions. Studies of other quality indicators in primary care can employ the triad to guide the analysis.