Background Improving communication between caregivers is an important approach to improving safety.

Objective To implement teamwork and communication interventions and evaluate their impact on patient outcomes.

Design A prospective, interrupted time series of a three-phase intervention: a run-in period (phase 1), during which a training programme was given to providers and staff on each unit; phase 2, which focused on unit-based safety teams to identify and address care problems using skills from phase 1; and phase 3, which focused on engaging patients in communication efforts.

Setting General medical inpatient units at three northern California hospitals.

Patients Administrative data were collected from all adults admitted to the target units, and a convenience sample of patients interviewed during and after hospitalisation.

Measurements Readmission, length of stay and patient reports of teamwork, problems with care, and overall satisfaction.

Results 10 977 patients were admitted; 581 patients (5.3% of total sample) were interviewed in hospital, and 313 (2.9% overall, 53.8% of interviewed patients) completed 1-month surveys. No phase of the study was associated with adjusted differences in readmission or length of stay. The phase 2 intervention appeared to be associated with improvement in reports of whether physicians treated them with respect, whether nurses treated them with respect or understood their needs (p<0.05 for all). Interestingly, patients were more likely to perceive that an error took place with their care and agreed less that their caregivers worked well together as a team. No phase had a consistent impact on patient reports of care processes or overall satisfaction.

Limitations The study lacks direct measures of patient safety.

Conclusions Efforts to simultaneously improve caregivers' ability to troubleshoot care and enhance communication may improve patients' perception of team functions, but may also increase patients' perception of safety gaps.