Hospital volume and patient outcomes. The case of hip fracture patients.

Patients achieve better outcomes at hospitals that treat larger numbers of patients with certain diagnoses or who are undergoing particular procedures. However, the causal direction underlying this relationship is less well understood. Do patients treated at institutions with higher volumes of patients achieve better outcomes because the hospital staff and physicians have gained expertise by practice (the "practice makes perfect" hypothesis)? Do hospitals with a community reputation for excellent results attract higher volumes of patients because primary care physicians refer patients to specialists who practice there (the "selective referral" hypothesis)? Or, are both explanations important? This article addresses this question through a detailed analysis of patients with a particular diagnosis: hip fracture. In addition, two measures of patient outcomes are compared: long hospital stays as a proxy for in-hospital complications and in-hospital death.

Hospital competition and surgical length of stay.

The hypothesis that competitive pressures encourage hospitals to accommodate patient and physician preferences for longer lengths of stay was tested. Seven hundred forty-seven nonfederal short-term hospitals were divided in terms of the number of neighboring hospitals within a 24-km radius, and this measure of hospital concentration and competition was measured against length of stay for ten surgical procedures, using 1982 data on 498454 patient discharges. Patient, physician, and hospital characteristics associated with length of stay were controlled for. Competition-related percentage increases in length of stay were identified for all procedures, including total hip replacement (14.8%), transurethral prostatectomy (13.9%), intestinal operations (14.0%), stomach operations (14.7%), hysterectomy (6.9%), cholecystectomy (9.1%), hernia repair (10.5%), appendectomy (8.4%), cardiac catheterization (22.9%), and coronary artery bypass graft surgery (21.2%). It was concluded that there is a strong association between the number of hospital competitors in the local market and the average length of stay in US hospitals.

Hospital competition, cost, and medical practice.

The hospital market in the United States has always been competitive, but the nature of that competition has changed in the last few years. In the past, when most patients had third party coverage which reimbursed hospitals for incurred costs, competition focused on quality and services as hospitals sought to attract physicians and their patients. This competition led to duplication of services and facilities in a "medical arms race" which resulted in higher, rather than lower, costs in areas with many hospitals. Hospitals with many neighbors even had longer lengths of stay for patients undergoing specific surgical procedures. Now, with Medicare's Prospective Payment System offering fixed payments for patients with a given diagnosis, there are strong pressures for cost containment. These pressures will have their greatest impact in areas with the most hospitals, especially when health maintenance organizations and preferred provider organizations contract selectively with some hospitals. Hospitals, in turn, will be less responsive to cost-increasing requests by their medical staffs.

Effects of surgeon volume and hospital volume on quality of care in hospitals.

A growing body of evidence indicates that certain surgical procedures exhibit a "volume-outcome" relationship in which a higher volume of patients undergoing a particular procedure at a hospital is associated with better outcomes for those patients. The proportion of a hospital's patients operated on by low-volume or less experienced surgeons also may be associated with poor patient outcomes and thus contribute to the hospital "volume-outcome" relationship. This paper analyzes the influence of hospital volume and the proportion of a hospital's patients operated on by low-volume surgeons on patient outcome for 10 procedures, controlling for other selected factors that may influence outcomes. The analysis is based on 503,662 patient abstracts from 757 hospitals. Results indicate that both hospital volume and the proportion of patients operated on by low-volume surgeons are related to quality of care as measured by patient outcomes. Higher hospital volume is positively related to better patient outcomes. These findings are consistent with earlier hospital "volume-outcome" research and add an additional set of procedures using more recent data to the evidence. Unlike previous research on surgeon volume, a positive relationship was found between higher percentage of patients operated on by low-volume surgeons and poorer hospital quality.

The volume-outcome relationship: practice-makes-perfect or selective-referral patterns?

Various studies have demonstrated that hospitals with larger numbers of patients with a specific diagnosis or procedure have lower mortality rates. In some instances, these results have been interpreted to mean that physicians and hospital personnel with more of these patients develop greater skills and that this results in better outcomes--the "practice-makes-perfect" hypothesis. An alternative explanation is that physicians and hospitals with better outcomes attract more patients--the "selective-referral pattern" hypothesis. Using data for 17 categories of patients from a sample of over 900 hospitals, we examine the patterns of selected variables with respect to hospital volume. To explore the plausibility of each hypothesis, a simultaneous-equation model is also used to test the relative importance of the two explanations for each diagnosis or procedure. The results suggest that both explanations are valid, and that the relative importance of the practice or referral explanation varies by diagnosis or procedure, in ways consistent with clinical aspects of the various patient categories.

Selective contracting for hospital care based on volume, quality, and price: prospects, problems, and unanswered questions.

There is a burgeoning interest in selective contracting for specialized hospital services based on volume, price, and quality. The systematic exclusion or inclusion of particular institutions has been extolled by some as an arrangement to reduce costs and by others as a means to increase quality of care. However, little is known about the issues and problems associated with selective contracting based on objective criteria rather than negotiations. Identification of individual institutions with performance significantly better or poorer than expected based on statistical norms is difficult and should be viewed as no more than a first step in evaluating quality and price performance. Actual data on 37 hospitals that provide coronary artery bypass graft surgery in a metropolitan region are used to illustrate some major prospects, problems, and situations arising when certain institutions are considered for exclusion from or inclusion in third-party payment programs. Selective contracting in local areas can potentially decrease duplication of services, reduce cost to purchasers, and lower expected mortality and morbidity for some patient groups. However, these gains must be evaluated against reductions in continuity of care and access to care, potential increases in mortality and morbidity for certain segments of the population, and substantial political problems.

Office visit patterns in physician group practices.

In summary, this study provides evidence that with as few as five diagnosis it is possible to identify some physician group practices that consistently treat patients with more or fewer visits, on average. However, even among group practices that vary considerably in size, location, and organizational structure, there is little deviation from the norm in terms of office visits. A study of more than 30 patients per site using data from both office records and insurance claims is needed, however, to examine the entire spectrum of treatment, including lab tests, special procedures, medications, and hospitalization. Such future studies may exploit the possibilities and avoid the pitfalls describes here to better characterize physicians' practice patterns.

Evaluating individual hospital quality through outcome statistics.

Case abstract data are routinely collected by hospital abstracting services, peer review organizations, and some state agencies. These data have proved invaluable in the analysis of patterns of performance across large numbers of hospitals and have shown, for example, the inverse relation between diagnosis- or procedure-specific volume and outcome. Routinely collected data also appear to be an attractive means for identifying hospitals, and perhaps physicians, with particularly good or poor outcomes for their patients. Unfortunately, problems of small numbers of patients and relatively low rates of poor outcomes make it difficult to be confident in the identification of individual performers. Recent data for cardiac catheterization patients are used to illustrate this problem.

Selecting categories of patients for regionalization. Implications of the relationship between volume and outcome.

A growing number of researchers have demonstrated an inverse relation between the number of patients treated with specific diagnoses or procedures in a hospital and subsequent adverse outcomes. Such findings support the notion that policies should be explored to concentrate patients in selected hospitals to reduce preventable patient mortality or morbidity. The authors used data from 15 diagnoses and procedures demonstrating an inverse relation between volume and mortality to explore the different implications of regionalization policies across categories of patients. In some instances, concentrating patients in hospitals with high volumes of such patients could avert more than 60% of all deaths. For some procedures or diagnoses, however, such mortality savings are either medically infeasible because of the emergency nature of the problem or logistically impossible because of the extent of regionalization implied.

Prognosis of imparied glucose tolerance in children with stress hyperglycemia, symptoms of hypoglycemia, or asymptomatic glucosuria.

Thirty-seven children and youths were ascertained because of stress hyperglycemia (3), asymptomatic glucosuria (21), or symptoms suggestive of hypoglycemia (13); 17 of them met the National Diabetes Data Group criteria for impaired glucose tolerance. Three ascertained because of glucosuria developed symptomatic insulin-dependent diabetes over the subsequent 14 months. They had more severe hyperglycemia and/or deficient insulin responses compared to those with normal tests or those with IGT who did not develop IDD. Insulin responses relative to glycemia were significantly age related and did not differ between the normal and IGT groups (excluding the three who developed IDD). The two-hour oral glucose tolerance test may be of value in young persons who have had stress hyperglycemia or asymptomatic glucosuria to rule out abnormality in a standardized manner or to detect preclinical IDD. Patients with autonomic symptoms may have transitory IGT as a concomitant manifestation of life stress; glucose tolerance testing of them appears unwarranted in the absence of other compelling symptoms or a family history of IDD.

Ten-year prognosis of impaired glucose tolerance in siblings of patients with insulin-dependent diabetes.

We traced 105 of 140 siblings of children with insulin-dependent diabetes (IDD) who had had oral glucose tolerance tests (OGTT) 10-12 yr earlier. Siblings with abnormal tests by screening criteria (8.3 mmol/L at 1 h, 7.2 at 2 h, N = 44) included all 6 who subsequently developed IDD after 3 mo to 7 yr (5.7% of entire group, 13.6% of abnormal screenees). The National Diabetes Data Group criterion for children (7.8 mmol/L at 2 h) identified 19 siblings, including 5 of the 6 who later developed IDD (26% of abnormals). Subsequent full 4-h OGTT, including analysis of insulin responses, did not improve predictability for subsequent IDD. Thus, siblings of IDD were identified at high risk (14-26%) or at low risk (0-1%) for subsequent IDD by a simple 2-h OGTT. The prolonged latency in the development of IDD indicates that, among siblings of IDD, this disorder may be already chronic for years by the time of clinical onset.