Impact of a statewide intensive care unit quality improvement initiative on hospital mortality and length of stay: retrospective comparative analysis

Abstract

Objective To evaluate whether implementation of the Michigan Keystone ICU project, a comprehensive statewide quality improvement initiative focused on reduction of infections, was associated with reductions in hospital mortality and length of stay for adults aged 65 or more admitted to intensive care units. Design Retrospective comparative study, using data from Medicare claims. Setting Michigan and Midwest region, United States. Population The study period (October 2001 to December 2006) spanned two years before the project was initiated to 22 months after its implementation. The study sample included hospital admissions for patients treated in 95 study hospitals in Michigan (238 937 total admissions) compared with 364 hospitals in the surrounding Midwest region (1 091 547 total admissions). Main outcome measures Hospital mortality and length of hospital stay. Results The overall trajectory of mortality outcomes differed significantly between the two groups upon implementation of the project (Wald test χ²=8.73, P=0.033). Reductions in mortality were significantly greater for the study group than for the comparison group 1-12 months (odds ratio 0.83, 95% confidence interval 0.79 to 0.87 v 0.88, 0.85 to 0.90, P=0.041) and 13-22 months (0.76, 0.72 to 0.81 v 0.84, 0.81 to 0.86, P=0.007) after implementation of the project. The overall trajectory of length of stay did not differ significantly between the groups upon implementation of the project (Wald test χ²=2.05, P=0.560). Group differences in adjusted length of stay compared with baseline did not reach significance during implementation of the project (−0.45 days, 95% confidence interval −0.62 to −0.28 v −0.35, −0.52 to −0.19) or during post-implementation months 1-12 (−0.59, −0.80 to −0.37 v −0.42, −0.59 to −0.25) and 13-22 (−0.67, −0.91 to −0.43 v −0.54, −0.72 to −0.37). Conclusions Implementation of the Keystone ICU project was associated with a significant decrease in hospital mortality in Michigan compared with the surrounding area. The project was not, however, sufficiently powered to show a significant difference in length of stay.