Percent Seeing a Primary Care Clinician Within 14 Days of Discharge

Readmission Rates For All Surgical Procedures 2010

Readmission rates within 30 days of initial discharge provide a measurement of quality of care as measured by:

• Percent readmitted within 30 days of discharge
• Percent readmitted within 30 days of discharge  as ratio to US average
• Percent seeing a primary care clinician within 14 days of discharge to home
• Percent having an emergency room visit within 30 days of discharge

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Three Step Process for Defining Hospital Service Areas

Hospital service areas were defined through a three-step process. First, all acute care hospitals in the 50 states and the District of Columbia were identified from the American Hospital Association and Medicare provider files and assigned to the town or city in which they were located. The name of the town or city was used as the name of the hospital service area, even though the area might have extended well beyond the political boundary of the town. For example, the Mt. Ascutney Hospital is in Windsor, Vermont. The area is called the Windsor hospital service area, even though the area serves several other communities.
 

In the second step, all 1992 and 1993 Medicare hospitalization records for each hospital were analyzed to ascertain the ZIP Code of each of its patients. When a town or city had more than one hospital, the counts were added together. Using a plurality rule, each ZIP Code was assigned on a provisional basis to the town containing the hospitals most often used by local residents.

The analysis of the patterns of use of care by Medicare patients led to the provisional assignment of five post office ZIP Codes to the Windsor hospital service area

ZIP Code	Community Name	1990 Population	% of Medicare Discharges to Mt. Ascutney Hospital
05037	Brownsville	415	52.8
05048	Hartland	1,730	46.8
05053	Pomfret	245	52.6
05062	Reading	614	36.8
05089	Windsor	5,406	63.2

The third step involved the visual examination of the ZIP Codes using a computer generated map to make sure that the ZIP Codes included in the hospital service areas were contiguous. In the case of the Windsor area, inspection of the map led to the reassignment of Pomfret to the Lebanon hospital service area. In the final determination, the Windsor hospital service area contained four communities and a total population of 8,165.

Map 1.1. ZIP Codes Assigned to the Windsor, Vermont, Hospital Service Area

The analysis of the pattern of use of hospitals revealed that Medicare enrollees living in the five ZIP Code areas in light blue most often used the Mt. Ascutney Hospital in Windsor, Vermont. To maintain geographic continuity of hospital service areas, the Pomfret ZIP Code 05053 was reassigned to the Lebanon hospital service area. The Windsor hospital service area contained four communities, with a 1990 census of 8,165. During 1992-93, there were 679 hospitalizations among the Medicare population; 394 (58%) were to Mt. Ascutney Hospital, 131 to the Mary Hitchcock Memorial Hospital, and 154 to other hospitals.

 

Defining Geographic Boundaries of Naturally Occurring Health Care Markets

The Medicare program maintains exhaustive records of hospitalizations, which makes it possible to define the patterns of use of hospital care. When Medicare enrollees are admitted to hospitals, the program’s records identify both the patients’ places of residence (by ZIP Code) and the hospitals where the admissions took place (by a unique numerical identifier). These files provide a reliable basis for determining the geographic pattern of health care use, because research shows that the migration patterns of patients in the Medicare program are similar to those for younger patients.

Medicare records of hospitalizations were used to define 3,436 geographically distinct hospital service areas in the United States. In each hospital service area, most of the care received by Medicare patients is provided in hospitals within the area. Based on the patterns of care for major cardiovascular surgery and neurosurgery, hospital service areas were aggregated into 306 hospital referral regions; this Blog reports on patterns of care in these hospital service areas (HSA) and hospital referral regions (HRR).

Geographic Variations in Health Care

Health services researchers have long been aware of large variations in the use of medical care among communities and regions. Insights into the geographic variation phenomenon, as presented in maps and other graphic displays, demonstrate once again that in health care markets, geography is destiny: the care one receives depends in large part on the supply of resources available in the place where one lives – and on the practice patterns of local physicians.

The existence of variation raises a number of important issues. Foremost is the question, “Which rate is right?” Which pattern of resource allocation, and which pattern of utilization, is “correct?” The study of practice variations reveals how complex this question really is. In the case of variations in rates of individual procedures, such as tonsillectomy and hysterectomy, the explanation is not that patients in areas with low procedure rates are going without treatment; they are, instead, being treated differently, often with more conservative medical management. Learning which rate is right requires learning what informed patients want. The right rate must be the one that reflects the choices of patients who have been adequately informed and empowered to choose among the available options.

This blog emphasizes using graphic displays of quantitative data to explore and better understand the geography of health and health care in the United States.