Association of National Hospital Quality Measure adherence with long-term mortality and readmissions

In existing studies, the association between adherence with recommended hospital care processes and subsequent outcomes has been inconsistent. This has substantial implications because process measure scores are used for accountability, quality improvement and reimbursement. Our investigation addresses methodological concerns with previous studies to better clarify the process-outcomes association for three common conditions.

The study included all patients discharged from Massachusetts General Hospital between 1 July 2004 and 31 December 2007 with a principle diagnosis of acute myocardial infarction (AMI), heart failure (HF) or pneumonia (PN) who were eligible for at least one National Hospital Quality Measure. The number of patients analysed varied by measure (374 to 3020) depending on Centers for Medicare and Medicaid Services eligibility criteria. Hospital data were linked with state administrative data to determine mortality and readmissions. For patients with multiple admissions, the time-weighted impact of measure failures on mortality was estimated using exponential decay functions. All patients had follow-up for at least 1 year or until death or readmission. Cox models were used to estimate HRs adjusted for transfer status, age, gender, race, census block-group socioeconomic status, number of Elixhauser comorbidities, and do not resuscitate orders.

Adjusted survival and freedom from readmission for AMI and PN showed superior results for 100% and 50-99% adherence compared with 0-49% adherence. For HF, the results were inconsistent and sometimes paradoxical, although several individual measures (eg, ACE inhibitor/angiotensin receptor blockade) were associated with improved outcomes.

Adherence with recommended AMI and PN care processes is associated with improved long-term outcomes, whereas the results for HF measures are inconsistent. The evidence base for all process measures must be critically evaluated, including the strength of association between these care processes and outcomes in real-world populations. Some currently recommended processes may not be suitable as accountability measures.