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Article Excerpt
The fact that patients admitted to the hospital on a weekend are more likely to die than patients admitted to the hospital on a weekday has stimulated renewed debate over the role of regulation versus incentives in enhancing the quality of health care. The apparent differences in weekend versus weekday care are substantial. A recent study found that, for certain medical conditions, patients admitted on the weekend were over 15 percent more likely to die in the hospital than patients admitted during the week (Bell and Redelmeier 2001). Because hospitals employ fewer nurses and other support staff on weekends, some researchers and policy makers attribute this "weekend effect" to hospitals' reductions in weekend staffing, and have recommended mandatory staffing legislation as a solution.
In this paper, I investigate an alternative hypothesis: that the weekend effect is caused by the delayed provision of specific intensive treatments which may be difficult to remedy with regulation alone. Under Medicare's reimbursement system, payments to hospitals are not related to the timeliness of treatment, or its suitability for a particular patient's health needs. Hospitals are reimbursed according to a patient's diagnosis-related group (DRG), which depends both on the patient's illness and the treatments provided by the hospital (McClellan 1997). The fixed-price DRG payment is determined by the mean cost across all hospitals of treating similar patients, and does not vary with the actual costs of treating a specific patient. As providing intensive treatment on the weekend may entail fixed costs, or higher marginal costs, it may be optimal for a hospital that sought to maximize revenues over costs to decline to do so. If the rapidity of intensive treatment has important effects on health outcomes for a sufficiently large number of patients, then this might not be in society's best interests.
Distinguishing between these hypotheses is a special case of an important general health policy problem: should observed shortfalls in quality be addressed with an input regulation or with a reimbursement system that rewards superior performance? Several states have passed legislation requiring that hospitals employ a minimum number of nurses and other support staff per patient at all times, which has substantially increased operating costs of hospitals. If understaffing causes the weekend effect, then intervention in the form of staffing ratios could be socially optimal. But if the weekend effect is caused by another form of inappropriate treatment not easily remedied through regulation, then stronger reimbursement incentives would be a more cost-effective policy response.
In this paper, I examine the impact of a weekend admission on the timing and incidence of specific intensive treatments received by elderly Medicare beneficiaries diagnosed with heart attack, or acute myocardial infarction (AMI). I explore how the timing of the three major invasive treatments associated with AMI--cardiac catheterization (CATH), angioplasty, and bypass surgery--varies for patients admitted on weekends and weekdays. I also examine the effects of weekend hospitalization on aggregate treatment intensity (1-year inpatient and outpatient expenditures) and adverse health outcomes (including mortality and cardiac related readmissions).
WEEKEND EFFECT: BACKGROUND
The existing empirical literature provides conflicting evidence regarding the relationship between weekend hospitalization, medical treatment decisions, and quality of care. Several studies conclude that weekend hospitalization is associated with worse health outcomes. The earliest research (MacFarlane 1978; Mangold 1981) examines the effect of weekend birth on neonatal or perinatal mortality, and finds higher mortality on the weekend than during the week. Bell and Redelmeier (2001) find significantly higher rates of in-hospital mortality for patients hospitalized on the weekend with one of three conditions (ruptured abdominal aortic aneurysm, acute epiglottitis, and pulmonary embolism) whose treatment was identified by the authors as being particularly sensitive to variations in staffing. The study also examines differences between weekend and weekday mortality for the top 100 diagnoses associated with in-hospital death. For 23 of these conditions the authors find evidence of significantly higher in-hospital mortality for patients admitted on the weekend. These studies are supported by other work that finds a positive correlation across hospitals between annual average staff-to-patient ratios and quality of care (Aiken et al. 2002; Needleman et al. 2002). Staffing is generally lower on the weekend, so evidence of a positive correlation between staffing and quality is consistent with an adverse weekend effect that operates through staffing.
Other researchers have argued that higher weekend mortality, at least in part, reflects differences in the unobservable characteristics of patients hospitalized on weekends versus weekdays. Because of the preferences of physicians and/or their patients for scheduled visits during the week, elective admissions are less likely to occur on weekends, which would lead patients admitted on the weekend to be sicker than those admitted during the week. More recent studies of neonatal mortality (Dowding et al. 1987; Gould et al. 2003) have found that higher weekend mortality results from the increased incidence of low-risk elective deliveries during the week, and the correspondingly higher proportion of high-risk, spontaneous weekend births. Halm and Chassin (2001) note that of the 23 conditions for which Bell and Redelmeier find evidence of higher in-hospital mortality, over half are cancers. Differences in short run outcomes between weekend and weekday patients admitted with nonacute illnesses are likely to be caused by unobserved differences in the health of such patients on admission. Consistent with this hypothesis, Dobkin (2003) finds no evidence of a weekend effect using data similar to those of Bell and Redelmeier, after controlling for patient heterogeneity.
A limited number of clinical studies have examined how day of week (and time of day) of admission might influence the use of specific medical treatments and health outcomes. A recent study by Magid et al. (2005) compares door-to-drug and door-to-balloon (angioplasty) times for patients admitted with acute ST-segment elevation myocardial infarction during "regular-hours" (Monday-Friday, 7:00 A.M.-5:00 P.M.) and "off-hours." Conditional on receiving reperfusion within 6 hours of hospitalization, patients admitted during off-hours periods face longer door-to-balloon times, but no significant difference in door-to-drug times. The authors find evidence of elevated in-hospital mortality for the pooled sample of off-hours patients receiving angioplasty or drug reperfusion, but do not find a significant effect on the in-hospital mortality for patients receiving angioplasty alone. By limiting their sample to patients who received reperfusion therapy within 6 hours, their analysis considers only the effects of delay conditional on receiving treatment, and does not explore how hospitalization during off-hours affects the mix of treatment patients receive.
Other research has explored the role of physician bias or "convenience" in medical decision making. Fraser et al. (1987), use data on all births at Royal Victoria Hospital in Montreal, Canada from 1978 to 1984 to examine the relationship between time of day and the rate of cesarean section. Controlling for duration of labor, they find significantly higher rates of cesarean section for dystocia during the evening hours (6:00 P.M.-11:59 P.M.). This is consistent with the convenience hypothesis--physicians prefer to perform these procedures in the evening hours rather than during the nighttime hours of sleep or the daytime hours when they have scheduled appointments with patients. Finally, Varnava et al. (2002) examine the effects of weekend hospital service reductions on the treatment of AMI patients in a British hospital. The authors observe substantially lower rates of discharge on weekends, suggesting that attending physicians prefer to be present on the day of discharge, but also prefer to be absent from the hospital on weekends.
In summary, one arm of existing research has documented correlations between mortality and either weekend admission or staffing, but has not identified whether these correlations are causal, and if they are, the mechanism through which they operate. In addition, the measures of outcomes used in this work have been either so short term as to fail to measure the likely consequences of weekend admission, or subject to important biases. Another arm has estimated the consequences of weekend admission on specific treatments, but has largely failed to explore the impact of these changes in treatment decisions for the cost and quality of care. Although policy makers have hypothesized that generalized reductions in staffing may be a source of excess weekend mortality in hospitals, there is little empirical evidence to support this claim. Without such evidence, the basis for regulatory intervention is weak at best.
DATA
The principal data used in my analysis are longitudinal claims from the 100 percent Medicare Provider Analysis and Review files, which are used to construct cohorts of nonrural, elderly Medicare beneficiaries hospitalized with a "new" diagnosis of AMI in 1989-1998....
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