A cost analysis of a Helicobacter pylori eradication strategy in a large health maintenance organization

OBJECTIVES

We sought to describe the effect of a Helicobacter pylori eradication strategy on health care costs among a cohort of health maintenance organization (HMO) members with peptic ulcer disease (PUD).

METHODS

Patients were identified from an outpatient diagnosis database and verified at chart review to have new-onset PUD by upper endoscopy or upper gastrointestinal radiographic series. Health plan registration and accounting databases were used to track costs over 12 months after initial diagnosis. Costs were analyzed separately for an initial 2-month interval and a 10-month follow-up period. Inpatient and pharmacy costs are those directly attributable to PUD (either a PUD-related discharge diagnosis or an antiulcer medication prescription). Outpatient costs are total costs. All cost differences were adjusted for age and gender.

RESULTS

Twenty-seven of 93 patients meeting selection criteria received H. pylori treatment. During the 2-month treatment window, adjusted PUD-related inpatient costs were higher for the H. pylori treated group (difference, $234.00/person), whereas total outpatient costs and PUD-related pharmacy costs were similar. During the 10-month follow-up period, PUD-related inpatient and pharmacy adjusted costs were similar, but adjusted outpatient costs in the H. pylori treated group were lower than in the untreated group (difference, $508.00/person). Total adjusted follow-up period costs were $555.00/person less in the H. pylori treated group (p = 0.05). Total 12-month costs in the H. pylori treated group were $285.00/per person less than in untreated patients, (p > 0.2); 30% of H. pylori treated patients were still receiving antisecretory therapy 1 yr after diagnosis, compared to 41.9% of untreated patients.

CONCLUSIONS

H. pylori treatment is associated with a decreased cost of follow-up care for patients with PUD, primarily due to decreased outpatient utilization.

Adult female twins' recall of childhood social class and father's education: a validation study for public health research

To assess recall of childhood socioeconomic position for public health research, the authors conducted a cross-sectional study of 352 adult women twin pairs enrolled in Examination II of the Kaiser Permanente Women Twins Study carried out in 1989-1990 in Oakland, California. Among twin pairs, 91% (95% confidence interval (CI) 89-94%) agreed on their father's educational level and 81% (95% CI 77-85%) on their childhood social class. Recall did not differ by adult socioeconomic position, zygosity, race/ethnicity, or age. Thus, epidemiologic studies can validly use retrospective data on childhood socioeconomic position to study its relation to adult health status.

Beta-blocker dosages and mortality after myocardial infarction: data from a large health maintenance organization

BACKGROUND

Although long-term beta-blocker therapy has been found beneficial in patients after an acute myocardial infarction, these drugs are greatly underused by clinicians. Moreover, the dosages of beta-blockers used in randomized controlled trials appear to be much larger than those routinely prescribed.

OBJECTIVE

To determine whether an association exists between the dosage of beta-blockers prescribed after a myocardial infarction and cardiac mortality.

METHODS

We performed a retrospective cohort study of 1165 patients who survived an acute myocardial infarction from January 1, 1990, through December 31, 1992. These patients represent a subgroup of the 6851 patients hospitalized at northern California Kaiser Permanente hospitals.

RESULTS

Of the 37.7% of patients prescribed beta-blocker therapy, 48.1% were treated with dosages less than 50% of the dosage found to be effective in preventing cardiac death in large randomized clinical trials (lower-dosage therapy). Compared with patients not receiving beta-blockers, those treated with lower-dosage therapy appeared to have a greater reduction in cardiovascular mortality (hazard ratio, 0.33; P=.009) than patients treated with a higher dosage (hazard ratio, 0.82; P=0.51), after adjustment for age, sex, race, disease severity, and comorbidities.

CONCLUSIONS

The dosages of beta-blockers shown to be effective in randomized trials are not commonly used in clinical practice, and treatment with lower dosages of beta-blockers was associated with at least as great a reduction in mortality as treatment with higher dosages. This suggests that physicians who are reluctant to prescribe beta-blockers because of the relatively large dosages used in the large prospective clinical trials should be encouraged to prescribe smaller dosages.

In a managed care setting, are there sex differences in the use of coronary angiography after acute myocardial infarction?

OBJECTIVES

The goal of this study was to examine sex differences in the use of coronary angiography after acute myocardial infarction in managed care facilities by using the American College of Cardiology/American Heart Association (ACC/AHA) practice guidelines (which incorporate clinical information on infarct complications, severity of illness, and comorbidity).

BACKGROUND

Although sex differences in the use of coronary angiography after acute myocardial infarction have been previously explored, the effects of indications for coronary angiography and common health insurance coverage on the sex and coronary angiography use relation have not been previously examined.

METHODS

This historical prospective study analyzed data collected from a random sample of 1133 patients (377 women, 756 men) from among 2740 patients hospitalized with validated acute myocardial infarction between Jan. 1, 1990, and Dec. 31, 1992, from seven of 16 Northern California Kaiser Facilities (three with high procedure rates for coronary angiography, four with low rates relative to the average region-wide utilization rate). In accordance with the guidelines, use of coronary angiography was determined for the in-hospital and "0 to 8 weeks" postdischarge periods. Patients were assigned time specific ACC/AHA classes for coronary angiography indications (I = highly indicated, IIA = probably indicated, IIB = not harmful, III = not indicated). The independent impact of ACC/AHA class, age, race, and facility on the sex and use of coronary angiography relation was examined by the Cox proportional hazard model.

RESULTS

Accounting only for ACC/AHA class, fewer women underwent coronary angiography compared with men among the "highly indicated" class I patients during the in-hospital period (43% vs 35%; p < 0.05), but not after discharge. Use of coronary angiography between the sexes was not statistically different among classes IIA, IIB, and III for both periods. After adjusting for differences in age, race, facility, and ACC/AHA class, we found no sex difference in in-hospital use of coronary angiography (hazard ratio (HR) = 1.02; 95% confidence interval [CI], 0.82 to 1.26), but among those discharged without receiving coronary angiography, women probably received fewer angiograms than did men (HR = 0.61; 95% CI, 0.37 to 1.00). For both periods, no significant sex difference in use of coronary angiography was found within ACC/AHA classes after adjustments.

CONCLUSION

In a setting where health insurance is prepaid and after controlling for ACC/AHA classification for coronary angiography indications, age, race, and facility, use of coronary angiography after myocardial infarction was similar among men and women during hospitalization, but was lower among women after discharge. Likely explanations for these differences in use of coronary angiography may include effects of physician judgment, patient decision, other social factors, or clinical information not captured in the practice guidelines.

Costs of acid-related disorders to a health maintenance organization

BACKGROUND

Little is known about the economic impact of the acid-related disorders (ARDs), which include dyspepsia, gastritis, gastroesophageal reflux disease (GERD), and peptic ulcer disease (PUD), in managed care patient populations.

OBJECTIVES

To describe the prevalence of medically attended ARDs, and their direct medical costs from the perspective of a large health maintenance organization (HMO).

METHODS

A total of 1,550 ARDs subjects (age > or = 18 years), were randomly sampled from outpatient diagnosis and pharmacy databases of the Kaiser Permanente Medical Care Program of Northern California and verified by chart review. Five age- and gender-matched controls were identified per subject. One-year prevalence, excess annual costs, and initial 6-month costs for incident cases were estimated using the HMO cost accounting system.

RESULTS

Total ARDs prevalence (5.8%) increases with advancing age. GERD is the most common ARD (2.9% overall prevalence). Annual per person attributable costs were $1,183, $471, and $431 respectively for PUD, GERD, and gastritis/dyspepsia. Excess inpatient costs for PUD explain its higher costs. Outpatient costs were somewhat higher for GERD ($279) than for PUD or gastritis/dyspepsia. Pharmacy costs were relatively low for each condition, in part because many patients were treated with generic cimetidine. Total annual HMO expenditures for ARDs were $59.4 million, with 40.6%, 36.8%, and 22.6% respectively for GERD, PUD, and gastritis/dyspepsia.

CONCLUSIONS

Acid-related disorders, particularly GERD and PUD, contribute substantially to the direct costs of medical care in this managed care population.

Choice of a personal physician and patient satisfaction in a health maintenance organization

CONTEXT

Being able to choose one's health care plan has been shown to increase subsequent patient satisfaction with the plan, but it is not known whether choosing one's own primary care physician affects patient satisfaction with the physician.

OBJECTIVE

To compare satisfaction with care between members of a group-model health maintenance organization (HMO) who chose their primary care physician and members who were assigned a physician.

DESIGN

Cross-sectional mailed survey with response rate of 71.4%.

SETTING

A large group-model HMO in northern California.

MAIN OUTCOME MEASURE

Nine questions on satisfaction with the primary care physician.

SUBJECTS

Random sample of HMO members 35 to 85 years of age who were impaneled with a primary care physician.

RESULTS

Among the 10205 survey respondents, patients who chose their personal physician (n=4748) were 16 to 20 percentage points more likely to rate their satisfaction as "excellent" or "very good" than patients who were assigned a physician (n =5457) for 9 satisfaction measures (P<.001 for each comparison). The association of choice with satisfaction was not due to physicians with higher patient satisfaction being chosen more often, or to differences in patient demographic or socioeconomic characteristics, health values, or health beliefs, or to differences in physician demographics or specialty. In a logistic regression model that adjusted for all of these characteristics, having chosen one's physician was the single predictor most strongly related to having high overall satisfaction (odds ratio, 2.18, 95% confidence interval, 1.95-2.42).

CONCLUSION

These results suggest that even in a setting of limited physician choice, the opportunity to select one's personal physician may influence subsequent satisfaction.

Influence of gender on cardiovascular mortality in acute myocardial infarction patients with high indication for coronary angiography

BACKGROUND

This study was undertaken to study gender differences in the use of coronary angiography (CA), revascularization (RV), and cardiovascular disease (CVD) mortality in patient with acute myocardial infarction (AMI) who were assigned to "High Indication for CA" per the American College of Cardiology/American Heart Association (ACC/ AHA) practice guidelines.

METHODS AND RESULTS

This is a historical prospective study based on a stratified random sample of 1165 AMI patients from January 1990 to December 1992 at seven health maintenance organization hospitals. CA was highly indicated in 286 women and 564 men. In a Cox hazard ratio (HR), women received significantly (P<.05) fewer CAs (HR, .78) and RVs (HR, .62) than men after adjusting for age, Charlson index, and congestive heart failure. Crude CVD mortality for women was higher than men (HR, 1.7). After adjustments for age, Charlson index, and congestive heart failure, the HR was reduced to 1.19 for women. Further adjustment for CA and RV lowered CVD mortality in women slightly (HR, 1.14). RV is associated with lowered CVD (HR, .41).

CONCLUSIONS

In patients with high indication for CA, use of CA and RV was significantly lower in women. After adjustments were made for risk profile and treatment modalities, women did not have a significantly increased risk for CVD compared with men. However, the apparent protective effect of RV in patients with a high indication for CA suggests that practices in line with ACC/AHA guidelines may reduce CVD in both women and men.

Insulin sensitivity and intake of vitamins E and C in African American, Hispanic, and non-Hispanic white men and women: the Insulin Resistance and Atherosclerosis Study (IRAS)

Elevated fasting insulin concentrations and insulin resistance have been associated with non-insulin-dependent diabetes mellitus (NIDDM), obesity, atherosclerosis, and hypertension. Vitamin E supplementation in persons with and without NIDDM may be related to greater insulin sensitivity (SI). The cross-sectional associations of the intake of vitamins E and C with SI and insulin concentrations were evaluated among African American, Hispanic, and non-Hispanic white men and women with a wide spectrum of glucose tolerance included in the Insulin Resistance and Atherosclerosis Study (IRAS) (n = 1151). Insulin sensitivity was measured by minimal model analysis of a 12-sample, insulin-modified, frequently sampled intravenous glucose tolerance test. Nutrient intake (including vitamin supplement use) was assessed with a food-frequency questionnaire modified to include foods consumed by the three ethnic groups. Linear-regression models were used, including rank of SI and the log of fasting insulin as the outcome variables. Pearson correlation coefficients for vitamins E and C in relation to rank SI were r = 0.07 (P = 0.01) and r = 0.07 (P = 0.02), respectively. After adjustment for total energy and BMI these associations were no longer statistically significant and did not differ between ethnic groups. Results were similar when vitamins E and C were combined in categories of low and high antioxidant intake. Models replicated with log of fasting insulin as the outcome variable also did not produce significant associations with vitamins E or C. Thus, these cross-sectional analyses do not support the hypothesis of improved SI with increased intake of vitamins E and C.

Linking automated databases for research in managed care settings

Spurred by demands for data from employer-purchasers and accreditation agencies and the adoption of strategies for disease management and outcome-based quality assurance, managed care organizations have recognized the need for rapid, convenient access to clinical information. Large investments in administrative and clinical data systems have also produced unprecedented opportunities for research on health care and epidemiology in large, defined populations. There is a long history of contributions to research by investigators who are based in the older nonprofit group and staff models of health maintenance organizations (HMOs). Many of these organizations maintain research units that are primarily funded by outside sources. Research includes descriptive and etiologic studies of epidemiology, randomized and observational studies of the effectiveness of treatment regimens, studies of disease costs and estimation of cost-effectiveness, investigations of risk predictions in populations, of risk and changes in organizational behavior, and evaluations of interventions to alter physician and patient behavior. The work is often conducted in collaboration with academic researchers. The HMO Research Network has recently been established to foster a scientific exchange among HMO-based researchers. As managed care organizations come to provide health care coverage to most U.S. citizens, research conducted by these organizations increasingly overlaps with public health research. Collaboration between HMO-based research centers and researchers from academia and government will undoubtedly continue to increase.

Effect of beta-adrenergic blocking agents on mortality rate in patients not revascularized after myocardial infarction: data from a large HMO

We investigated whether patients who do not undergo coronary angiography and therefore any form of revascularization after a myocardial infarction derive greater benefit from chronic beta-blocker therapy than patients who undergo coronary angiography. With multivariate analyses, treatment with beta-blockers was a much stronger predictor of survival in patients who did not undergo coronary angiography (relative risk = 0.38, p = 0.005) than in those patients who did undergo catheterization (p < 0.05 for interaction). Our findings provide direct support for the recommendation by the American College of Cardiology/American Heart Association task force that beta-blocker therapy should be initiated for all infarct survivors who do not undergo revascularization and who have no contraindications.

Excess costs of medical care for patients with diabetes in a managed care population

OBJECTIVE

To estimate the excess costs of medical care for patients with diabetes in a managed care population and to determine the proportion of costs spent on treating the complications of diabetes.

RESEARCH DESIGN AND METHODS

A comparison of 1-year (1994) costs of medical care in the 85,209 members of the diabetes registry of Kaiser Permanente, Northern California, and in 85,209 age- and sex-matched nondiabetic control subjects. Costs were obtained from automated program databases. Costs specifically related to treating acute and long-term complications of diabetes were identified, and the excess costs attributable to each complication in individuals with diabetes were calculated.

RESULTS

Excess expenditures in individuals with diabetes totaled $282.7 million, or $3,494 per person. Per person expenditures for members with diabetes were 2.4 times those for matched control subjects. The largest proportion of total excess costs was for hospitalizations within the health maintenance organization (38.5%). Nearly 38% of the total excess was spent treating the long-term complications of diabetes, predominantly coronary heart disease and end-stage renal disease.

CONCLUSIONS

Diabetes is a costly condition by virtue of its high prevalence and high per person costs. A large proportion of these costs are related to treating complications of diabetes. Available evidence indicates that several measures can reduce complication rates. Thus, effective disease management programs that aim to prevent complications could potentially lead to cost savings in managed care settings.

The impact of aging and chronic disease on use of hospital and outpatient services in a large HMO: 1971-1991

OBJECTIVES

To examine overall and diagnosis-specific trends in the use of inpatient and outpatient medical services (1970-1988) among older members of a large HMO.

DESIGN

Two cohorts of approximately 3000 persons aged 65 or older in 1971 and 1980 were compared for hospital and outpatient utilization during 9-year follow-up periods (1971-79 and 1980-88). All subjects were evaluated for vital status throughout the follow-up period as well.

PARTICIPANTS

All 6057 subjects were members of the Northern California Kaiser Permanente Medical Care Program in 1971 or 1980. The study sample was sex-age stratified (65-69,70-79,80+) at baseline.

MEASUREMENTS

Data on demographics, outpatient health services utilization, categories of outpatient utilization and disease diagnoses were obtained from membership lists or medical chart review; inpatient utilization, including admitting and discharge diagnosis, length of stay, and number of hospital days was assessed from computerized hospitalization records.

RESULTS

Hospital discharge rates (sex-age adjusted) increased by 12% between cohorts, with the largest increases at the oldest ages. There was a 25% increase among women and a 9% increase among men. Length of stay decreased by 20%. Hospitalization for ischemic heart disease decreased by 17%. Congestive heart failure (CHF) discharge rates (sex-age adjusted) were 92% higher in the 1980-88 cohort. For diagnoses related to nursing home institutionalization and frailty, discharge rates were significantly higher in the 1980-88 cohort: pneumonia (+34%), urinary tract infections (+104%), dehydration (+110%), osteoarthritis (+64%), syncope (+246%), leg cellulitis (+70%). In-hospital survival improved, but overall percent of readmissions also increased by 4%; readmissions for CHF increased by 13% and those for conditions of frailty by 120%. Overall outpatient visits increased by 17%. Use of laboratory tests (+57%) and outpatient surgeries (+99%) increased for all age strata in 1980-88 compared with 1971-79.

CONCLUSIONS

While overall outpatient and inpatient utilization has largely decreased over the past 30 years, as a result of economic factors and improved treatments for some major diseases, there has been an increase in utilization among older people. Hospitalization for diagnoses associated with end-stage cardiovascular disease (CHF), musculoskeletal disease, frailty and iatrogenic aspects of institutionalization are clearly increasing substantially. The largest impact of aging on health care may be the result of institutionalization and its sequelae. Improved treatment for cardiovascular disease may also be leading to increased utilization at later stages in the disease process.

The Colon Cancer Prevention Program (CoCaP): rationale, implementation, and preliminary results

Although there is now solid evidence to support the efficacy of colorectal cancer screening, few health care systems have developed comprehensive screening programs. This report describes the scientific rationale, development and implementation strategies, and preliminary results of the Colon Cancer Prevention Program (CoCaP) of the Northern California Region of the Kaiser Permanente Medical Care Program. CoCaP is a sigmoidoscopy-based screening program that aims to provide screening to all average-risk program members once every 10 years beginning at age 50. During the first 2 years of the program, more than 100,000 sigmoidoscopies were performed in age-eligible members (age 50 years and above). Seventy-five percent of these were screening examinations. Participating endoscopists include gastroenterologists, generalist physicians, and a growing number of non-physicians, primarily nurses, nurse-practitioners or physicians' assistants. Data on depth of insertion and polyp yield suggest that non-physicians quickly become as proficient as physician endoscopists. The long-term goals of the CoCaP program are to reduce the incidence of and mortality from colorectal cancer. Collection and analysis of data from the screening examinations and follow-up colonoscopies will enable CoCaP to refine its screening algorithm and to quantify program effectiveness.

Differences in insulin suppression of free fatty acid levels by gender and glucose tolerance status. Relation to plasma triglyceride and apolipoprotein B concentrations. Insulin Resistance Atherosclerosis Study (IRAS) Investigators

Most discussions of relations of insulin resistance to coronary heart disease risk factors have focused on insulin-stimulated glucose uptake, but insulin suppression of plasma free fatty acid (FFA) levels is also important in lipid and lipoprotein metabolism. To identify groups with impaired insulin suppression of FFAs, we studied a multiethnic cohort of 1521 women and men at four US centers that comprise the Insulin Resistance Atherosclerosis Study (IRAS): 682 with normal glucose tolerance, 352 with impaired glucose tolerance, and 487 with non-insulin-dependent diabetes. The FFA level 2 hours after a 75-gm oral glucose load adjusted for fasting FFAs was used as the measure of insulin suppression. After adjustment for age, center, ethnicity, body mass index, and fasting and 2-hour insulin levels, 2-hour FFA levels were significantly higher in men than women and in persons with impaired glucose tolerance and non-insulin-dependent diabetes mellitus versus normal glucose tolerance. The gender difference was largely accounted for by differences in central obesity as measured by waist-hip ratio; the difference by glucose tolerance status was not affected by central obesity, suggesting a different mechanism. In multivariate regression analyses, 2-hour FFA levels were strongly related to fasting triglyceride and apoB levels, respectively, after adjustment for age, fasting and 2-hour insulin concentrations, and fasting FFA concentrations. In summary, elevated plasma apoB and triglyceride concentrations associated with male gender and with glucose intolerance are partly accounted for by differences in the ability of insulin to suppress FFA concentrations.

Variation among hospitals in coronary-angiography practices and outcomes after myocardial infarction in a large health maintenance organization

BACKGROUND

Wide geographic variation in the use of coronary angiography after myocardial infarction has been documented internationally and within the United States. An associated variation in clinical outcomes has not been consistently demonstrated.

METHODS

We assessed the risk of death from heart disease and of any heart disease event (death, reinfarction, or rehospitalization) over a follow-up period of one to four years in 6851 patients hospitalized with acute myocardial infarction at 16 Kaiser Permanente hospitals from 1990 through 1992. The percentage of patients who underwent angiography within three months after infarction ranged from 30 to 77 percent. We selected a subcohort of 1109 patients from three hospitals with higher rates of angiography and four with lower rates for a record review to assess the severity of infarction, the number of coexisting conditions, treatments received, and the appropriateness and necessity of angiography, using established criteria.

RESULTS

The rates of angiography were inversely related to the risk of death from heart disease (P= 0.03) and the risk of heart disease events (P<0.001) among the 16 hospitals after adjustment for age, sex, race, coexisting conditions, and the location of the infarction (subendocardial vs. transmural). In the subcohort, 440 patients met criteria indicating that angiography was necessary and 669 did not. Among the former, patients treated at hospitals with higher rates of angiography had a lower risk of death and of any heart disease event than those treated at hospitals with lower rates (hazard ratios, 0.67 and 0.72, respectively). Among the latter, the apparent benefits of being treated at hospitals with higher angiography rates were smaller (hazard ratios, 0.85 to 0.90 for death and any heart disease event, respectively).

CONCLUSIONS

During the one to four years after myocardial infarction, patients treated at hospitals with higher rates of angiography had more favorable outcomes than those treated at hospitals with lower rates. This association was stronger among patients for whom published criteria indicated that angiography was necessary.

Insulin sensitivity and abdominal obesity in African-American, Hispanic, and non-Hispanic white men and women. The Insulin Resistance and Atherosclerosis Study

Increased abdominal obesity has been related to lower insulin sensitivity (SI), independent of overall obesity, but it has been suggested that this relationship may be weaker in non-whites. In the Insulin Resistance and Atherosclerosis Study (IRAS), SI was estimated using a minimal model analysis of the frequently sampled intravenous glucose tolerance test in 1,625 men and women aged 40-69 years. Subjects included African-Americans, Hispanics, and non-Hispanic whites from Oakland and Los Angeles, CA, San Antonio, TX, and the San Luis Valley, CO. Minimum waist circumference was significantly (P = 0.0001) associated with SI after adjusting for age, sex, height, BMI, glucose tolerance status, ethnicity, and clinic. This relationship was significantly (P = 0.0001) stronger in subjects with normal glucose tolerance (NGT) (beta = -0.030, P = 0.0001) than in those with impaired glucose tolerance (IGT) (beta = -0.010, P = 0.02; NIDDM: beta = -0.013, P = 0.0001). There were no significant ethnic differences in effect size across the spectrum of glucose tolerance. Waist circumference was also positively related to fasting insulin, an indirect measure of insulin sensitivity, in NGT (P = 0.0001), IGT (P = 0.0003), and NIDDM (P = 0.0002). The waist-fasting insulin relationship was significantly weaker in African-Americans, relative to non-Hispanic whites, in NGT and IGT (tests of statistical interaction: P = 0.04 and P = 0.02, respectively). In general, these patterns were similar in models specifying waist-to-hip ratio (WHR), rather than waist circumference, as the independent variable. While some ethnic variability exists, a negative relationship between abdominal obesity and insulin sensitivity was confirmed for all three ethnic groups across the spectrum of glucose tolerance.

Trends in cardiovascular disease incidence and survival in the elderly

This study compared the age-specific incidence, postdiagnostic survival, and mortality for cardiovascular disease (CVD) in two cohorts of people aged 65 years and older. All subjects were members of a large prepaid health maintenance organization. The influence of changes in CVD risk factors on these rates also was evaluated. Trends in prevalence, incidence, postdiagnostic survival, and mortality for CVD were examined in both cohorts in 1971 and 1980. Myocardial infarction (MI), angina pectoris, stroke, and congestive heart failure (CHF) were included as CVD outcomes in this analysis. Nine-year prospective data on these diagnoses were abstracted from medical records and computerized hospitalization records for both cohorts. Age-sex-adjusted cardiovascular mortality was lower for both sexes by approximately 20% in the 1980 cohort. Overall survival did not change, whereas cancer mortality increased by 76% in women and 36% in men. With the exception of stroke, there was no increase in age-adjusted or age-specific prevalence. In men, the age-adjusted prevalence of stroke in men was 24% higher in the 1980 cohort. Age-adjusted 9-year incidence of MI, angina pectoris, stroke, and CHF did not change between cohorts in either sex Postdiagnostic, age-adjusted mortality for men with incident stroke was 24% lower in the 1980 cohort, and Postdiagnostic, age-adjusted mortality for men with incident angina was 35% lower in the 1980 cohort. Adjustment for risk factors measured at or before baseline had little influence on cohort differences in CVD incidence or duration of survival after CVD diagnosis. This study confirms other research showing a decline in CVD mortality over the past 20 years. These findings suggest that prevalent angina pectoris is increasing in men, and that survival with stroke and with angina is improving in men. Later diagnosis of incident CHF in men suggests that prevention and early detection may be postponing the development of more serious disease.

Insulin sensitivity and atherosclerosis. The Insulin Resistance Atherosclerosis Study (IRAS) Investigators

BACKGROUND

Reduced insulin sensitivity has been proposed as an important risk factor in the development of atherosclerosis. However, insulin sensitivity is related to many other cardiovascular risk factors, including plasma insulin levels, and it is unclear whether an independent role of insulin sensitivity exists. Large epidemiological studies that measure insulin sensitivity directly have not been conducted.

METHODS AND RESULTS

The Insulin Resistance Atherosclerosis Study (IRAS) evaluated insulin sensitivity (SI) by the frequently sampled intravenous glucose tolerance test with analysis by the minimal model of Bergman. IRAS measured intimal-medial thickness (IMT) of the carotid artery as an index of atherosclerosis by use of noninvasive B-mode ultrasonography. These measures, as well as factors that may potentially confound or mediate the relationship between insulin sensitivity and atherosclerosis, were available in relation to 398 black, 457 Hispanic, and 542 non-Hispanic white IRAS participants. There was a significant negative association between SI and the IMT of the carotid artery both in Hispanics and in non-Hispanic whites. This effect was reduced but not totally explained by adjustment for traditional cardiovascular disease risk factors, glucose tolerance, measures of adiposity, and fasting insulin levels. There was no association between SI and the IMT of the carotid artery in blacks. The association between SI and the IMT was stronger for the internal carotid artery than for the common carotid artery in all ethnic groups.

CONCLUSIONS

Higher levels of insulin sensitivity are associated with less atherosclerosis in Hispanics and non-Hispanic whites but not in blacks. This effect is partially mediated by traditional cardiovascular risk factors.

The polyp prevention trial I: rationale, design, recruitment, and baseline participant characteristics

The Polyp Prevention Trial (PPT) is a multicenter randomized controlled trial examining the effect of a low-fat (20% of total energy intake), high-fiber (18 g/1000 kcal), high-vegetable and -fruit (5-8 daily servings) dietary pattern on the recurrence of adenomatous polyps of the large bowel, precursors of most colorectal malignancies. Eligibility criteria include one or more adenomas removed within 6 months of randomization; complete nonsurgical polyp removal and complete colonic examination to the cecum at the qualifying colonoscopy: age 35 years of more; no history of colorectal cancer, inflammatory bowel disease, or large bowel resection; and satisfactory completion of a food frequency questionnaire and 4-day food record. Of approximately 38,277 potential participants with one or more polyps recently resected, investigators at eight clinical centers randomized 2,079 (5.4%; 1,037 in the intervention and 1,042 in the control arm) between June 1991 and January 1994, making the PPT the largest adenoma recurrence trial ever conducted. Of PPT participants, 35% are women and 10% are minorities. At study entry, participants averaged 61.4 years of age; 14% of them smoked, and 22% used aspirin. At the baseline colonoscopy, 35% of participants had two or more adenomas, and 29% had at least one large (> of = 1 cm) adenoma. Demographic, behavioral, dietary, and clinical characteristics are comparable across the two study arms. Participants have repeat colonoscopies after 1 (T(1)) and 4 (T(4)) years of follow-up. The primary end point is adenoma recurrence; secondary end points include number, size, location, and histology of adenomas. All resected lesions are reviewed centrally by gastrointestinal pathologists. The trial provides 90% power to detect a reduction of 24% in the annual adenoma recurrence rate. The primary analytic period, on which sample size calculations were based is 3 years (T(1) to T(4)), which permits a 1-year lag time for the intervention to work and allows a more definitive clearing of lesions at T(1), given that at least 10-15% of polyps may be missed at baseline. The final (T(4)) colonoscopies are expected to be completed in early 1998.

Effect of a copayment on use of the emergency department in a health maintenance organization

BACKGROUND

Use of the emergency department for nonemergency care is frequent and costly. We studied the effect of a copayment on emergency department use in a group-model health maintenance organization (HMO).

METHODS

We examined the use of the emergency department in 1992 and 1993 by 30,276 subjects who ranged in age from 1 to 63 years at the start of the study and belonged to the Kaiser Permanente HMO in northern California. We assessed their use of various HMO services and their clinical outcomes before and after the introduction of a copayment of $25 to $35 for using the emergency department. This copayment group was compared with two randomly selected control groups not affected by the copayment. One control group, with 60,408 members, was matched for age, sex, and area of residence to the copayment group. The second, with 37,539 members, was matched for these factors and also for the type of employer.

RESULTS

After adjustment for age, sex, socioeconomic status, and use of the emergency department in 1992, the decline in the number of visits in 1993 was 14.6 percentage points greater in the copayment group than in either control group (P<0.001 for each comparison). Visits for urgent care did not increase among subjects in any stratum defined by age and sex, and neither did the number of outpatient visits by adults and children. The decline in emergency visits for presenting conditions classified as "always an emergency" was small and not significant. For conditions classified as "often an emergency". "sometimes not an emergency", or "often not an emergency", the declines in the use of the emergency department were larger and statistically significant, and they increased with decreasing severity of the presenting condition. Although our ability to detect any adverse effects of the copayment was limited, there was no suggestion of excess adverse events in the copayment group, such as increases in mortality or in the number of potentially avoidable hospitalizations.

CONCLUSIONS

Among members of an HMO, the introduction of a small copayment for the use of the emergency department was associated with a decline of about 15 percent in the use of that department, mostly among patients with conditions considered likely not to present an emergency.

Genetic and environmental influences on insulin levels and the insulin resistance syndrome: an analysis of women twins

Multiple factors may determine insulin resistance and the insulin resistance syndrome. The contributions of genes and environment to the distribution of fasting insulin levels and to the associations of fasting insulin with elements of the syndrome were evaluated in the second examination of the Kaiser Permanente Women Twins Study (Oakland, California, 1989-1990). Subjects included 556 white women (165 monozygous twin pairs, 113 dizygous pairs; 455 women with normal glucose tolerance, 75 with impaired glucose tolerance, and 26 with non-insulin-dependent diabetes by World Health Organization criteria). The intraclass correlation coefficients for log fasting insulin for monozygous and dizygous twin pairs were 0.64 and 0.40, respectively. After adjustment for age, behavioral factors, and body mass index, the estimated classic heritability was 0.53 (p = 0.003). Commingling analysis of fasting insulin indicated the presence of four distributions (p < 0.001), consistent with at least one, and perhaps two, genes influencing this trait. In an unmatched multiple regression model among women from monozygous twin pairs only, log fasting insulin was independently associated with body mass index (p < 0.0001), waist/hip ratio (p = 0.02), and glucose intolerance (p = 0.04), but not with triglycerides, high density lipoprotein cholesterol, or hypertension. After removal of genetic influences by analysis of monozygous intrapair differences, only body mass index (p < 0.0001) remained independently related to fasting insulin. The authors conclude that, in addition to significant genetic influences on fasting insulin, environmental or behavioral factors (particularly nongenetic variation in obesity) are important determinants of fasting insulin and the insulin resistance syndrome.