Does evidence-based practice improve patient outcomes? An analysis of a natural experiment in a Spanish hospital

Evidence-based practice (EBP) is widely promoted, but does EBP produce better patient outcomes? We report a natural experiment when part of the internal medicine service in a hospital was reorganized in 2003 to form an EBP unit, the rest of the service remaining unchanged. The units attended similar patients until 2012 permitting comparisons of outcomes and activity.

We used routinely collected statistics (2004-11) to compare the two different methods of practice and test whether patients being seen by the EBP unit differed from standard practice (SP) patients. Data were available by doctor and year. To check for differences between the EBP and SP doctors prior to reorganization, we used statistics from 2000 to 2003. We looked for changes in patient outcomes or activity following reorganization and whether the EBP unit was achieving significantly different results from SP. Data across the periods were combined and tested using Mann-Whitney test.

No statistically significant differences in outcomes were detected between the EBP and the SP doctors prior to reorganization. Following the unit's establishment, the mortality of patients being treated by EBP doctors compared with their previous performance dropped from 7.4% to 6.3% (P < 0.02) and length of stay from 9.15 to 6.01 days (P = 0.002). No statistically significant improvements were seen in SP physicians' performance. No differences in the proportion of patients admitted or their complexity between the services were detected. Despite this, EBP patients had a clinically significantly lower risk of death 6.27% versus 7.75% (P < 0.001) and a shorter length of stay 6.01 versus 8.46 days (P < 0.001) than SP patients. Readmission rates were similar: 14.4% (EBP); 14.5% (SP). EBP doctors attended twice as many patients/doctor as SP doctors.

The EBP unit was associated with better patient outcomes and more efficient performance than achieved by the same physicians previously or by SP concurrently.