Table 2. Risk of bias summary table.

Trial	Selection bias	Allocation concealment	Performance bias	Detection bias	Attrition bias	Selective reporting	Other bias	Quality
Bell et al.20	Yes—there were ethnic differences between suburban and rural practices; however, clustering would have helped to control for this	No allocation concealment	Yes—there was no blinding for users	Unclear—no mention of blinding of outcome assessors	Unclear as to how many of the patients enroled at each practice remained in the trial—pragmatic design, denominator quite flexible, withdrawals not reported.	Unclear—no pre-published protocol.	No	C—high risk
Eccles et al.21	No—minimised by computerised randomisation of practices in a cluster design	No allocation concealment	No—GPs were acting as controls for the other block	No—data collectors were blinded to the status of practice	No—attrition rates were presented and balanced; there were 31 intervention practices and 29 control practices who completed the study and two withdrawals.	No—a pre-published protocol-outlined plan for data analysis and embedded case study and economic evaluation.	No	A—low risk
Fiks et al.22	Unclear—no details of randomisation	No allocation concealment	Yes—no blinding, clinicians were aware that their software either did or did not have the alerts	Unclear—no mention of blinding of outcome assessors	No—attrition fairly balanced—no patients withdrew; however, there was fluctuation in the numbers of patients, as may be expected in such a large cohort.	Unclear—possibility of post hoc analysis of vaccination rates to achieve higher rates—no pre-published analysis protocol.	No	C—high risk
Kuilboer et al.23	No—randomisation performed with a table of random numbers by a researcher who was blinded to the identity of practices	No allocation concealment	Yes—there was no blinding for GP users	Unclear—no mention of blinding of outcome assessors	No—flow diagram explains why patients dropped out or withdrew. No attrition at practice level.	Unclear—no pre-published protocol.	No	C—high risk
Martens et al.24,28	Unclear—no details of randomisation	Yes—GPs blinded as to whether they were assessed on treatment of cholesterol or asthma and COPD	No—GPs did not know that they were acting as controls for the other block	Unclear—no mention of blinding of outcome assessors	No—attrition was fairly balanced but resulted in the study being underpowered. Reasons for attrition were given.	Unclear—no pre-published protocol.	No	B—moderate risk
McCowan et al.25	No—randomisation using random number sequence and performed independently of the project administration team	No allocation concealment	Yes—there was no blinding of GPs	Unclear—no mention of blinding of outcome assessors	No—attrition was unbalanced and although most practices gave some reasons this resulted in the study being underpowered and intention-to-treat analysis was impossible due to insufficient information.	Unclear—no pre-published protocol.	No	C—high risk
Plaza et al.26	No—randomisation using SAS (statistics programme). Patients were recruited as they came for consultation	No allocation concealment	Unclear, not reported	Unclear—no mention of blinding of outcome assessors	No—clinician withdrawals reported (2/22) due to administrative problems, patient withdrawals also reported in diagram.	Unclear—no pre-published protocol.	No	C—high risk
Tierney et al.27	No—randomisation by flip coin, then switching to equal numbers of consultations per arm by a researcher blinded to allocation.	No allocation concealment for professionals or patients	Yes—there was no blinding of GPs	Unclear—no mention of blinding of outcome assessors	No—flow diagram explains why patients dropped out or withdrew. Attrition appeared to be fairly balanced.	Yes—no pre-published protocol and post hoc analysis of power calculation.	No	C—high risk

Abbreviations: COPD, chronic obstructive pulmonary disease; GP, general practitioner.