Carlson 1991.

Methods	RCT (incomplete block design randomised by practices; 2 groups of practices (where nurses were involved or nurses were not involved) were randomised in two groups) Randomisation concealment: NOT CLEAR Follow up: ‐ providers: NOT CLEAR ‐ patients: NOT DONE Blinded assessment: DONE for HbA1c NOT CLEAR for measurements of professional practice Baseline: NOT CLEAR Reliable outcomes: DONE for HbA1c NOT CLEAR for measurements of professional practice Protection against contamination: DONE unit of analysis error
Participants	34 primary health care centres (PHCC) in the Stockholm area in Sweden Patients who had visited the PHCC during the 12 months prior to the evaluation (not clear which type of diabetes) providers‐ ? (mixed: physicians, nurses, nurse assistants, managers, administrators, laboratory technicians) patients ‐ 4492 (measurements on professional practice) patients ‐ 566 (measurements on HbA1c) practices ‐ 3
Interventions	Intervention group: Professional intervention (educational meetings + local consensus processes to identify problems and to create plans to improve diabetes care + educational outreach visits) Control group: usual care Length of intervention: 18 months Follow up period: lasted 12 months
Outcomes	PROCESS: ‐Patients height noted in case notes during previous year ‐HbA1c value measured during previous year: ‐Eye examination performed during previous year PATIENT: HbA1c
Notes	A national Diabetes Control Program was initiated in 1979 ‐directed at organization of care ‐ target glycaemic control and care routines as measured by audit of case records
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear