Variation in the Reporting of Elective Surgeries and Its Influence on Patient Safety Indicators

US hospital safety is routinely measured via Patient Safety Indicators (PSIs). Receiving a score for most PSIs requires a minimum number of qualifying cases to meet specific criteria; for example, whether an admission was elective. Because admission type is determined by hospitals' internal policies, the study team suspected that hospitals may be exempted from elective-based PSI scores as a result of their internal admission classification policies.

Multiple regression was combined with machine learning to analyze Medicare inpatient claims data reported by 3,484 hospitals during the 2015-2017 PSI measurement period. The researchers examined the average percentage of elective admissions across surgical diagnosis-related groups (DRGs) (average percent elective [APE]) in relation to hospital characteristics, surgical claims volumes, and numbers and types of surgical DRGs. This study asked whether hospitals with exceptionally low APE shared particular characteristics, reported claims for similar DRGs, or were disproportionately exempted from elective-based PSIs.

Cross-validated multiple regression explained 73.9% of variation in APE among hospitals and identified surgical claims volume and 16 surgical DRGs as consistently important variables. However, the exceptionally low APE of 96 hospitals could not be explained by surgical claims volume, surgical DRGs among claims, or hospital characteristics. These outliers were disproportionately exempt from elective-based PSI scores.

Some hospitals may have classified admissions in a way that exempted them from elective-based PSI scores. Transparency into admission classification policies is needed to ensure fair and reliable use of PSIs when ranking hospitals and adjusting payments. Alternatively, PSIs may need modifications to rely on externally validated criteria.