Study name | Developing and applying appropriate eligibility criteria | Measurement of exposure | Measurement of outcome | Controlling for confounding | Completeness of data |
---|---|---|---|---|---|
Boltri et al,10 2002 | Low risk Physicians and residents in the control and exposed groups were from the same pool | Low risk Policy applied across the clinic | Low risk Data collection was based on medical records, and carried out by a research assistant blinded to study design and hypothesis | Low risk ‘Logistic regression was then performed to adjust the odds ratio for the relation of physician type, prescribing patterns, and time’ | Low risk No missing data reported |
Spurling and Mansfield,12 2007 | Low risk Diaries chosen at random for a 1-month period. A random week was chosen for auditing doctors’ prescribing | Low risk Policy applied across the clinic | Unclear risk Not clear whether the survey instrument was validated | High risk According to the authors, the possibility of confounding cannot be ruled out | Low risk. All except one returned the completed questionnaire |
Hartung et al,11 2010 | Unclear risk | Low risk Policy applied across the clinic | Unclear risk Use of claim data; however, validity of the data not described | Low risk They include ‘a contemporaneous control group of patients or clinicians also experiencing this potential confounder’ (confounding resulting from secular changes in prescribing) | Low risk ‘Although it is possible that some prescriptions would not have been captured by using data from only one pharmacy, it seems unlikely that this subset would have introduced any systematic bias or loss of generalisability’ |