Adverse Patient Safety Events: Costs of Readmissions and Patient Outcomes Following Discharge Didem M. Bernard, Ph.D. William E. Encinosa, Ph.D.

Patient Safety Events IoM estimated that between 44,000 and 98,000 people die in hospitals each year as a result of medical errors IoM estimated that between 44,000 and 98,000 people die in hospitals each year as a result of medical errors Medical errors is the eighth leading cause of death in the U.S. Medical errors is the eighth leading cause of death in the U.S. IoM recommended at least a 50% reduction in medical errors over 5 years IoM recommended at least a 50% reduction in medical errors over 5 years

Background Medical injuries during hospitalizations lead to excess length of stay, charges and mortality (Zhan and Miller, 2003) Medical injuries during hospitalizations lead to excess length of stay, charges and mortality (Zhan and Miller, 2003) Whether adverse patient safety events have a significant impact on patient outcomes and costs following discharge is less clear Whether adverse patient safety events have a significant impact on patient outcomes and costs following discharge is less clear

Research Questions Do adverse patient safety events during hospitalizations have an effect on patient outcomes following discharge? Are there long-term costs associated with potentially preventable adverse medical events?

Patient Safety Indicators We use the AHRQ Patient Safety Indicators (PSI) developed by the UCSF- Stanford Evidence-Based Practice Center (EPC) and UC-Davis (2003). We use the AHRQ Patient Safety Indicators (PSI) developed by the UCSF- Stanford Evidence-Based Practice Center (EPC) and UC-Davis (2003). EPC selected 14 indicators among 63 complication indicators using EPC selected 14 indicators among 63 complication indicators using – Indicator validity results from the literature – Empirical analyses of the precision and reliability of the candidate PSIs – Review of potential indicators by 11 clinical panels

Patient Safety Indicators 1 1 Anesthesia Complications * 2 2 Accidental Puncture or Laceration During Procedure 3 3 Foreign Body Left In During Procedure* 4 4 Hemorrhage or Hematoma 5 5 Wound Dehiscence 6 6 Infection Due to Medical Care 7 7 Pulmonary Embolism and Deep Vein Thrombosis * Labeled as medical errors

Patient Safety Indicators (cont.) 8 8 Iatrogenic Pneumothorax* 9 9 Acute Respiratory Failure Sepsis Physiologic and Metabolic Derangements Transfusion Reaction Hip Fracture* Decubitus Ulcer* * Labeled as medical errors

Data 2002 California Hospital Discharge Data AHRQ Healthcare Cost and Utilization Project (HCUP) State Inpatient Database (SID) Hospital Inpatient Cost to Charge Ratios Area Wage Index (CMS) Number of Hospitals: 349

Analytic Sample and Methods Major Surgery Discharges (17<age<65) Major Surgery Discharges (17<age<65) From February 1, 2002 to November 30, 2002 Index admission: A major surgery admission with no hospitalizations in a 30 day window prior to the admission date (N=602,361) Index admission: A major surgery admission with no hospitalizations in a 30 day window prior to the admission date (N=602,361) Readmission: Any hospitalization within 30 days of initial discharge Readmission: Any hospitalization within 30 days of initial discharge

Patient Outcomes Probability of readmissions Probability of readmissions Probability of death during index admission Probability of death during index admission Probability of death during any readmission within 30 days of initial discharge Probability of death during any readmission within 30 days of initial discharge

Costs of Adverse Patient Safety Events Index admission costs Index admission costs Costs of readmissions Costs of readmissions Total costs for index admissions and readmissions within 30 days following discharge Total costs for index admissions and readmissions within 30 days following discharge

Basic Model: Hospital Costs i=person y= cost of hospitalization* PSI= (0,1) indicator equals 1 if patient has at least one adverse patient safety event x=control variables * Index admission, readmission or total hospital costs

Basic Model: Patient Outcomes i=person y=(0,1) indicator equals 1 if patient is readmitted within 30 days of discharge* PSI= (0,1) indicator equals 1 if patient has at least one adverse patient safety event x=control variables * y=(0,1) indicator equals 1if patient dies during hospitalization

Control Variables Patient: age, sex, race/ethnicity, transfer admission, emergency admission, 30 chronic conditions, MDC, zipcode level median household income Patient: age, sex, race/ethnicity, transfer admission, emergency admission, 30 chronic conditions, MDC, zipcode level median household income Hospital: teaching status, ownership type, bedsize Hospital: teaching status, ownership type, bedsize Market: Health Service Area dummies Market: Health Service Area dummies

Patient Outcomes PSI=0 PSI=0 PSI=1 PSI=1 Live discharge 84.55% 84.55% 63.03% 63.03% Death during index admission 0.86% 0.86% 5.97% 5.97% Readmission 14.14% 14.14% 28.32% 28.32% Death during readmission 0.46% 0.46% 2.68% 2.68% N 583, ,836 18,889 18,889

Average Costs Index Hospitalization Index HospitalizationReadmission Total Costs PSI=0 $12,579 $12,579 $17,927 $17,927 $15,198 $15,198 PSI=1 $31,096 $31,096 $33,445 $33,445 $41,510 $41,510 Difference 147% 147% 87% 87% 173% 173%

Estimation Costs: GLM (Generalized Liner Method) log-link with Gamma distribution (Manning and Mullahy, 2001) Costs: GLM (Generalized Liner Method) log-link with Gamma distribution (Manning and Mullahy, 2001) Patient Outcomes: Logit regressions Patient Outcomes: Logit regressions Simulation results: Simulation results: A : Predicted costs/outcomes with PSI=1 B : Predicted costs/outcomes with PSI=0 (A – B) : Predicted costs/outcomes due to adverse patient safety events

Simulation Results: Outcomes Death during index hospitalization Death during index hospitalization Death during readmission Death within 30 days of discharge PSI=0 0.92% 0.92% 3.4% 3.4% 1.4% 1.4% PSI=1 1.96% 1.96% 5.2% 5.2% 2.8% 2.8% % Difference 1.04%* 1.04%* 1.8%* 1.8%* 1.4%* 1.4%* * Significantly different from zero at the 99% level

Simulation Results: Outcomes (cont.) Probability of Probability of readmission readmission PSI=0 15.1% 15.1% PSI=1 20.1% 20.1% Difference 5.0%* 5.0%* * Significantly different from zero at the 99% level

Simulation Results: Costs Index Hospitalization Index HospitalizationReadmission Total Costs PSI=0 $12,801 $12,801 $18,264 $18,264 $15,618 $15,618 PSI=1 $21,190 $21,190 $26,198 $26,198 $26,607 $26,607 PSI COST $8,388* $8,388* (232) (232) $7,933* $7,933* (529) (529) $10,989* $10,989* (284) (284) % Difference 65.5% 65.5% 43.4% 43.4% 70.4% 70.4% * Significantly different from zero at the 99% level

Summary Excess costs and adverse outcomes of adverse patient safety events are not limited to the initial hospitalization Excess costs and adverse outcomes of adverse patient safety events are not limited to the initial hospitalization Adverse patient safety events during hospitalizations lead to Adverse patient safety events during hospitalizations lead to – Higher probability of readmissions – Higher probability of in-hospital death following discharge – Higher inpatient costs following discharge

Policy Implications A reduction in adverse patient safety events will not only improve quality of care but also reduce long-term health care costs