Estimation of seroprevalence, rape, and homelessness in the United States using a social network approach.

The authors have developed and tested scale-up methods, based on a simple social network theory, to estimate the size of hard-to-count subpopulations. The authors asked a nationally representative sample of respondents how many people they knew in a list of 32 subpopulations, including 29 subpopulations of known size and 3 of unknown size. Using these responses, the authors produced an effectively unbiased maximum likelihood estimate of the number of people each respondent knows. These estimates were then used to back-estimate the size of the three populations of unknown size. Maximum likelihood values and 95% confidence intervals are found for seroprevalence, 800,000 +/- 43,000; for homeless, 526,000 +/- 35,000; and for women raped in the last 12 months, 194,000 +/- 21,000. The estimate for seroprevalence agrees strikingly with medical estimates, the homeless estimate is well within the published estimates, and the authors' estimate lies in the middle of the published range for rape victims.

Complications after laparoscopic cholecystectomy.

After becoming alarmed about seven unusual and severe complications reported by New York State hospitals after laparoscopic cholecystectomy, the Department of Health of New York State tabulated all reported adverse incidents. After observing unusual injuries to the great vessels of the abdomen and an increase in major bile duct injury during laparoscopic cholecystectomy, the Department of Health prepared a memorandum to New York State hospitals advising closer attention to education, credentialing, proctoring, and outcome after these operations. The frequency of cholecystectomy has increased sharply, by 21%, since the advent of laparoscopic cholecystectomy. The serious injury rate may be approximately 15 times that observed after an open cholecystectomy. Recognizing the theoretic advantages of the procedure, the Department of Health reminded hospital Boards of Trustees of their obligation to establish mechanisms for credentialing and privileging surgeons and surgical teams so that the risks do not exceed those expected of the open procedure and to detect and correct deviations from this standard.

A longitudinal analysis of the relationship between in-hospital mortality in New York State and the volume of abdominal aortic aneurysm surgeries performed.

This study uses New York State hospital discharge data to examine the relationship between in-hospital mortality for a patient receiving an abdominal aortic aneurysm resection and the volume of aneurysm operations performed in the previous year at the hospital where the operation took place and by the surgeon performing the operation. Previous research on this topic is extended in several respects: (1) A three-year data base is used to examine the manner in which hospital and surgeon volume jointly affect mortality rate and to examine ruptured and unruptured aneurysms separately; (2) a six-year data base is used to study the "practice makes perfect" hypothesis and the "selective referral" hypothesis; and (3) the degree of specialization of high-volume surgeons is contrasted with that of other surgeons. The results demonstrate a significant inverse relationship between hospital volume and mortality rate for unruptured aneurysms. Further, very few surgeons substantially increased their aneurysm surgery volumes in the six-year study period. Weak selective referral effects were found for both surgeons and hospitals, and higher-volume aneurysm surgeons tended to have much higher specialization rates.

Gender differences in mortality rates for coronary artery bypass surgery.

This study utilized a state-wide data base containing clinical risk factors for cardiac surgery to investigate differences in in-hospital mortality rates for men and women undergoing coronary artery bypass surgery. The crude mortality rates for coronary artery bypass surgery for men and women were 3.08% and 5.43% respectively, in New York State in 1989. When logistic regression analysis was used to control for preoperative risk, gender remained a significant predictor of mortality. Risk-adjusted (indirectly standardized) mortality rates were 3.33% and 4.45% for men and women, respectively. The risk-adjusted odds ratio of women to men experiencing in-hospital death was 1.52 (95% confidence interval 1.25 to 1.90).

Investigation of the relationship between volume and mortality for surgical procedures performed in New York State hospitals.

Recent studies have demonstrated that the number of times a hospital or surgeon performs certain procedures annually has an inverse relationship with in-hospital mortality rates for patients undergoing the procedures. This study uses an improved measure of physician volume to test the combined relationship of hospital and physician volume with in-hospital mortality rates and to explore the existence of threshold volumes that optimally discriminate high- and low-volume providers. Five procedure groups have significant volume-mortality relationships. For total cholecystectomies, hospital volume is the more significant volume measure, but physician volume is marginally related to mortality rate. For coronary artery bypass surgeries, resection of abdominal aortic aneurysms, partial gastrectomies, and colectomies, physician volume is more significant than hospital volume, but hospital volume is marginally significant. Annual hospital volume thresholds for these data appear to exist at approximately 5 procedures for partial gastrectomies, 40 procedures for colectomies, and 170 procedures for total cholecystectomies.

A methodology for targeting hospital cases for quality of care record reviews.

We tested the efficacy of selected case characteristics in targeting quality of care problems for medical record review. The case characteristics, all of which apply to patients who die in a hospital, consist primarily of procedures and DRGs (diagnosis-related groups) for which death rarely occurs, and a set of complications of surgical care. All characteristics are obtainable from combinations of the principal and secondary diagnoses and procedures in the case, and are available from discharge abstracts. The presence of a quality of care problem is confirmed through a review of the medical record by a nurse and two or more physicians. A logistic regression model that controls for various patient and hospital variables is used as a measure of each of the proposed case characteristics. The results indicate that most of the characteristics are associated with higher percentages of quality of care problems than cases chosen at random, and that the methodology has promise as a tool for targeting cases for medical record review.

Increased oxygen uptake following phlebotomy and simultaneous fluid replacement in polycythemic patients.

To study the isolated effects of decreased hemoglobin concentration without volume loss, eight patients with the diagnosis of polycythemia were studied following acute phlebotomy and simultaneous volume replacement. These patients had been treated previously by repeated phlebotomy, without volume replacement, to a hemoglobin level of 14.8 +/- 0.5 gm%. Following hemodilution by additional phlebotomy and volume replacement, which further lowered the mean hemoglobin level to 11.4 +/- 0.4 gm%, cardiac index increased significantly from 2.8 +/- 0.3 to 3.5 +/- 0. 3 liter/min/m(2) (P<0.05), oxygen delivery did not change, but total body oxygen consumption increased significantly from 140 +/- 16 to 180 +/- 15 ml/min/m(2) (P<0.05). Mixed venous PO2, systemic and pulmonary vascular resistance decreased significantly (P<0.05). Vascular pressure, heart rate, intrapulmonary shunt, arterial pH and bicarbonate, limb blood flow, limb oxygen delivery and limb oxygen consumption did not change. Thus, with phlebotomy and fluid replacement, a reduction of hemoglobin concentration to a subnormal level increased oxygen consumption without lowering oxygen delivery.

Colonic infusion in the management of the short bowel syndrome.

Two cases are presented of short bowel syndrome. Both had had the colon or part of the colon bypassed as part of prior surgical management in addition to having had extensive resection of the small bowel. Despite various medical regimens, both patients remained in negative fluid and electrolyte balance thus requiring intravenous fluid supplementation. In an effort to maintain positive fluid balance without intravenous therapy, colonic infusion of fluids was initiated. This modification of management proved effective in maintenance of adequate plasma volume and normal renal function. It is concluded that this type of therapy can be of great benefit in the management of patients with the short bowel syndrome.