Gardner 1991.

Methods	Controlled before‐after study
Participants	138 nurses working on medical units in a 526‐bed urban tertiary care teaching hospital. Medical patients on the study units for more than 2 days, understood English and fitted into one of 3 cardiac Diagnosis Related Groups (DRGs) (DRG 121, DRG 122, DRG 127), or were in the same room as patients with one of these DRGs.
Interventions	Intervention: primary nursing ‐ concepts operationalised using the Manthey 1980 definition of primary nursing ‐ used to train, educate and guide staff on a daily basis. Control: units using team nursing
Outcomes	Quality of nursing care Hospital stress rating Nurses' support Retention of RNs Mean DRG relative cost weights DRG cost by length‐of‐stay
Country/Setting	USA: Rochester General Hospital Rochester, New York
Notes	Retention of nurses was the only outcome relevant to this study. The study was supported by the Pew Charitable Trusts, ref: 86:0506HE. No interests declared.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Not done ‐ CBA
Allocation concealment (selection bias)	High risk	Not done ‐ CBA
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding procedures not discussed ‐ probably not done.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding procedures not discussed ‐ probably not done.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All outcomes were reported.
Selective reporting (reporting bias)	Unclear risk	Study protocol not available. Cost per patient day analysis separated old wing and new wing primary vs team nursing costs (excluded new wing primary group to find a statistically significant result) (P‐hacking?).
Baseline characteristics similar for intervention group and control?	Unclear risk	Limited information provided about the baseline characteristics. However, participants with similar DRGs were used across the units and it was reported that "in the pre intervention phase, all units had comparable staffing and patient mix and used a functional/team nursing model". Nursing stress scale, direct nursing care time baseline data not reported. Baseline mean and SD scores provided for qualpacs, Hospital Stress Rating Scale (HSRS) and Nursing Support Scale (NSS).
Other bias	Unclear risk	Change in study setting could have effects on outcomes. No report of sensitivity analyses having been conducted.