A variable-radius measure of local hospital market structure

OBJECTIVE

To provide a radius measure of the structure of local hospital markets that varies with hospital characteristics and is available for all hospitals in the United States.

DATA SOURCES

1982 American Hospital Association (AHA) Survey of Hospitals, 1982 Area Resource File (ARF), and 1983 California Office of Statewide Health Planning and Development (OSHPD) discharge abstracts.

STUDY DESIGN

The OSHPD data were used to measure the radii necessary to capture 75 percent and 90 percent of each hospital's admissions. These radii were used as the dependent variables in regression models in which the independent variables were from the AHA and ARF. To estimate predicted market radii, the estimated parameters from the California models were applied to all nonfederal, short-term, general hospitals in the continental United States. These radii were used to define each hospital's service area, and all other hospitals within the calculated radii were considered potential competitors. Using this definition, we calculated two measures of local market structure: the number of other hospitals within the radius and a Herfindahl-Hirschman Index based on the distribution of hospital bed shares in the market.

DATA EXTRACTION METHODS

These measures were calculated for all nonfederal, short-term, acute care hospitals in the continental United States for whom complete data were available (N = 4,884).

CONCLUSIONS

These measures are available from the authors on computer-readable diskette, matched to hospital identifiers.

Urethral pressure variation in women with vulvar vestibulitis syndrome

OBJECTIVES

It is hypothesized that patients with vulvar vestibulitis syndrome will demonstrate increased urethral pressure variability.

STUDY DESIGN

Twelve patients with confirmed vulvar vestibulitis syndrome were compared with two groups: 13 patients with chronic pelvic pain matched for age and race and 23 asymptomatic unmatched patients. Urodynamic variables studied included maximum urethral pressure, functional urethral length, bladder capacity, and urethral pressure variability. During urethral pressure measurement each patient was given a standard mental exercise.

RESULTS

Urethral pressure variability was significantly greater in patients with vulvar vestibulitis than in those with chronic pain or in asymptomatic controls (Wilcoxon test, p < 0.001). Use of a multiple regression model that controlled for age, race, and parity showed that diagnostic group predicted a significant degree of urethral pressure variability (F = 8.18, p < 0.001).

CONCLUSIONS

Vulvar vestibulitis syndrome is associated with increased urethral pressure variability, and variation in muscular tone of the urethra is the probable source of this variability. However, the possible relationship with the pathogenesis of vulvar vestibulitis syndrome is unknown at present.

DNA methylation of the fragile X locus in somatic and germ cells during fetal development: relevance to the fragile X syndrome and X inactivation

To obtain insights into mechanisms responsible for methylation of CpG islands on the inactive X chromosome of normal females, we examined methylation of the fragile X (FraX) locus in a variety of tissues from normal fetuses and adults, and from males with the FraX syndrome. We identified 20 CCGG sites (MspI-HpaII sites M1-M20) within a 12-kb BglII fragment that includes the CpG island. Sites M3-M18, within the 1.2-kb CpG island are unmethylated on the active X in normal males and females at all ages and in all tissues studied. In contrast, these sites are at least partially methylated on the inactive X chromosome in a variety of tissues from normal females by six weeks from conception. The exceptional tissues are chorionic villi and gonads, which are significantly undermethylated. In addition, fetal germ cells are unmethylated at site M3, which is methylated on the inactive X in other tissues; thus, the methylation imprint of the inactive X has been erased. Methylation of the locus on the fragile X chromosome is similar to that of the normal inactive X but is more extensive and less heterogeneous. This suggests that the expansion of the island and the greater number of CpGs that result from amplification of the CGG repeat enhance the methylatibility of the island. Additional studies show that the chromatin of the CpG island is nuclease hypersensitive on the active X but insensitive on both inactive and FraX.

Health plan switching in anticipation of increased medical care utilization

We compare rates and days of maternity and nonmaternity hospital admission for the years 1981 through 1984 for three groups of employees and dependents from a large private employer: those continuously enrolled in a fee-for-service (FFS) plan (N = 147,700), those continuously enrolled in a health maintenance organization (HMO) (N = 30,957), and those switching from the FFS plan to the HMO (N = 2,144). The rate of maternity admissions for plan switchers increased by 106% (P < 0.001) in the post-switch year compared with the pre-switch year, while maternity rates for continuing FFS-plan enrollees declined by 12% (P < 0.001) and rates for continuing HMO enrollees remained unchanged. Nonmaternity admission rates for switchers decreased by 19% (P = 0.079), consistent with the expectation that HMOs reduce these rates substantially, while rates for FFS-plan stayers increased 4% (P < 0.001) and those for HMO stayers remained unchanged. We conclude that employees often switch health plans when anticipating increased needs for maternity care and therefore that pre-switch rates of utilization are unreliable measures of the true magnitude of risk selection between HMOs and FFS plans.

Dose-dependent suppression of aqueous humor formation by timolol in the cynomolgus monkey

The effect of topical timolol on the fluorophotometrically determined aqueous humor formation rate in the cynomolgus monkey was studied. A timolol dose of 2.5, 5, 15, 30, 45, 90, or 180 $mUg was administered as a single topical dose to one eye of five monkeys. Postdrug flow rates were compared with no-drug baselines obtained on separate occasions. Our findings were that (a) topical timolol decreases aqueous humor formation rates in a dose-dependent fashion, with 30 $mUg and 50% flow suppression at or near the top of the single dose-response curve; (b) there is a significant contralateral effect, and only at extremely low doses can treated versus control eye effects be separated; and (c) doses as small as 2.5 $mUg can suppress aqueous formation by a statistically significant 20%. In the monkey, as in the human, timolol is a far more potent suppressor of aqueous formation than is generally realized, and standard clinical doses may in fact be overdoses in both species.

Partner-specific condom use among adolescent women clients of a family planning clinic

Because inconsistent condom use could put adolescent women at an increased risk for sexually transmitted diseases, it is important to understand when and with whom they use condoms. This study examined partner-specific condom use over time among adolescent women. The data were from a clinic-based, prospective study of 308 adolescent women who had at least one sex partner during a 6-month follow-up. Their condom use was examined with three types of partners: exclusive, nonexclusive primary, and nonexclusive secondary. Predictors of consistent condom use (using condoms 100% of the time with a specific partner) were explored in a multiple logistic regression analysis. Consistent condom use was more likely to occur in shorter relationships (less than 3 months) and with partners who preferred condoms for contraception. It was no more likely to occur with nonexclusive partners than with exclusive partners, and it was somewhat less likely to occur among consistent oral contraceptive users. These findings emphasize the importance of educating adolescent women to introduce and maintain condom use with all partners.

Progressive systemic sclerosis causing rapidly progressive myocardial disease and death

We have presented an unusually swift progression of progressive systemic sclerosis (PSS), with death from cardiogenic shock in a 22-year-old woman who had severe hypertension and acute renal insufficiency. She arrived at our hospital with pericardial tamponade and shock. Despite initial improvement after pericardiocentesis, the patient's condition soon deteriorated and she died of cardiogenic shock. PSS was diagnosed at autopsy. Although the course of PSS is frequently indolent, it may also be fulminant, leading to death before diagnosis is determined.

Effects of stressful life events on bowel symptoms: subjects with irritable bowel syndrome compared with subjects without bowel dysfunction

A standardised inventory of stressful life events and a bowel symptom questionnaire were administered at three month intervals for one year to 383 women who were unselected with respect to bowel symptoms. A NEO Personality Inventory was given initially to assess neuroticism. Subjects who satisfied restrictive diagnostic criteria for irritable bowel syndrome were compared with those who complained of abdominal pain plus altered bowel habits but who did not meet restrictive diagnostic criteria (functional bowel disorder) and with controls without bowel dysfunction. The irritable bowel group showed significantly higher levels of stress than the other two groups even when the confounding effects of neuroticism were statistically controlled for. Time lagged correlations showed that stress in one three month interval was significantly correlated with bowel symptoms in the subsequent three month interval for all groups. The slope of the regression line relating stress to bowel symptoms was significantly steeper for the irritable bowel group than for the other two groups at three and six months, suggesting that subjects with irritable bowel syndrome show a greater reactivity to stress. Stress scores were also significantly correlated with the number of disability days and the number of medical clinic visits for bowel symptoms.

Dysmenorrhea and use of oral contraceptives in adolescent women attending a family planning clinic

OBJECTIVES

This study examined the prevalance of dysmenorrhea in female adolescents and the effect of experiencing a reduction in dysmenorrhea on oral contraceptive use.

STUDY DESIGN

This was a prospective panel study in which 308 adolescent women at an inner-city family planning clinic were interviewed about their experiences with dysmenorrhea and their oral contraceptive use at three points in time over a 6-month period. A chi 2 test and multiple logistic regression analysis were done.

RESULTS

The overall prevalence of dysmenorrhea in this population was 79.6%; 18.2% reported severe dysmenorrhea. Those who had severe dysmenorrhea and also experienced the reduction of dysmenorrhea as a result of oral contraceptives were eight times more likely to be consistent oral contraceptive users (p less than or equal to 0.02).

CONCLUSIONS

It is important to screen female adolescents for dysmenorrhea, provide them with information about the beneficial side effects of oral contraceptives, and follow up these young women to make sure they are experiencing the alleviation of their symptoms.

Superior cervical ganglionectomy in monkeys: surgical technique

Seven cynomolgus monkeys underwent a histologically confirmed left superior cervical ganglionectomy (SCGx). Unilateral ocular sympathetic denervation persisting for at least 2 yr was confirmed by ipsilateral ptosis, miosis, supersensitivity of pupillary dilation to topical phenylephrine, and profound pupillary hyporesponsiveness to topical hydroxyamphetamine. Intraocular pressure 8-9 and 23-27 months postoperatively were identical in the denervated and contralateral control eyes. This model should facilitate studies of aqueous humor physiology and pharmacology.

The role of threshold limit values in U.S. air pollution policy

This paper analyzes the role of threshold limit values (TLVs) in national air pollution policy during the 1980s, a period in which the Environmental Protection Agency (EPA) sought to delegate to individual states the authority to evaluate and regulate airborne toxic substances. We focus on 20 carcinogens and 11 substances with non-genotoxic health effects that were regulated by local air toxics programs using TLVs. Data from EPA's National Air Toxics Information Clearinghouse indicate that maximum TLV-based Ambient Air Level guidelines (AALs) frequently exceed minimum TLV-based AALs by a factor of greater than 1,000. Cancer potency data from EPA's Integrated Risk Information System suggest significant risks remain at TLV-based AALs. Cancer risks at the median TLV-based AAL exceed 1,000 cases per million exposed persons for cadmium (1,040), nickel and its compounds (1,420), propylene oxide (1,550), coke oven emissions (1,860), benzene (2,500), arsenic and its compounds (7,300), N-nitrosodimethylamine (21,000), asbestos (21,500), and ethylene dibromide (55,000). We also summarize published studies that report non-genotoxic health effects in workers exposed at levels near the TLV for 11 substances whose AALs were based on TLVs. Contrary to the assumption frequently made by state air toxics program, TLVs cannot be taken to represent no observed effect levels (NOELs) for regulatory purposes.

HMO market penetration and hospital cost inflation in California

OBJECTIVE--Health maintenance organizations (HMOs) have stimulated price competition in California hospital markets since 1983, when the state legislature eliminated barriers to selective contracting by conventional health insurance plans. This study measures the impact of HMO-induced price competition on the rate of inflation in average cost per admission for 298 private, non-HMO hospitals between 1982 and 1988. DATA--HMO market penetration was calculated using discharge abstract data on insurance coverage, ZIP code of residence, and hospital of choice for 3.35 million patients in 1983 and 3.41 million patients in 1988. Data on hospital characteristics were obtained from the American Hospital Association and other sources.

RESULTS

-HMO coverage grew from an average of 8.3% of all admissions in local hospital markets in 1983 to 17.0% of all admissions in 1988. The average rate of growth in costs per admission between 1982 and 1988 was 9.4% lower in markets with relatively high HMO penetration compared with markets with relatively low HMO penetration (95% confidence interval, 5.2 to 13.8). Cost savings for these 298 hospitals are estimated at $1.04 billion for 1988. CONCLUSION--Price competition between HMOs and conventional health insurers can significantly reduce hospital cost inflation if legislative barriers to selective contracting are removed. The impact of competition in California was modest, however, when evaluated in terms of the 74.5% average rate of California hospital cost inflation during these years.

From health-based to technology-based standards for hazardous air pollutants

The Clean Air Act Amendments of 1990 represent a major shift in regulatory emphasis for toxic air pollutants. Recognizing the immediate public health benefits that can be gained from the application of currently available and affordable control technologies, Congress has abandoned its insistence that health risks should be the only consideration in establishing emissions standards. Previously excluded concerns about economic costs and technological feasibility will now determine the initial level of pollution control required of toxic air pollution sources. In exchange for reducing the stringency of emissions limits, the newly amended act extends the scope of regulation by listing 189 toxic substances that must be controlled over the next decade. This exchange of regulatory depth for breadth occurs against a history of reluctance by the Environmental Protection Agency to implement the original health-protective language of the Clean Air Act. It mirrors earlier compromises under the Clean Water Act and the Occupational Safety and Health Act.

Cytochalasin B potentiates epinephrine's outflow facility-increasing effect

Total outflow facility was determined in both eyes of cynomolgus monkeys by two-level constant pressure perfusion. After a baseline measurement, one eye of the experimental animal received intracameral cytochalasin B (CB); the other eye received vehicle without CB. Twenty minutes later both eyes received intracameral epinephrine (EPI), and 30 min later the outflow facility was again determined. Doses of CB and EPI which were subthreshold when given singly produced significant facility increases when given concurrently. Subthreshold doses of CB given concurrently with a maximal dose of EPI produced significantly larger facility increases than a maximal dose of EPI given alone. A maximal dose of CB produced a larger facility increase than a maximal dose of EPI. Maximal doses of CB and EPI given concurrently produced a larger facility increase than did a maximal dose of EPI alone and had about the same effect as a maximal CB dose given alone. Since CB's facility-increasing effect is likely due to "disruption" of actin filaments in the endothelial cells of the trabecular meshwork and Schlemm's canal and since CB potentiates the facility-increasing effect of EPI, EPI may also act by "disrupting" actin filaments and consequently altering endothelial cell shape.

Programmed demethylation in CpG islands during human fetal development

The mechanism for establishing the DNA methylation patterns observed in adult mammalian tissues is not well understood. To determine when adult patterns are established for housekeeping genes, we examined the clustered CpGs in genes on the human active X chromosome (PGK, G6PD, P3, GdX, HPRT) and the autosomal gene, DHFR. We find unique methylation patterns present at the P3 locus in all tissues analyzed from 6- to 9-week fetal specimens, and at the HPRT locus in adrenal gland DNA at this stage of development. Adult patterns are established subsequently by demethylating specific CpGs. Our results show that demethylating events affecting CpG islands are programmed during mammalian fetal development. They suggest that the process of de novo methylation in the fetus methylates at least some sites in the 3' region of the CpG islands in active genes and that adult patterns are established at 6-14 weeks developmental age by sequence-specific demethylation.

Consistency of condom use for disease prevention among adolescent users of oral contraceptives

A six-month prospective study examined consistency of condom use for disease prevention among 308 adolescent women who had received a prescription for oral contraceptives at a family planning clinic. Only 16 percent used condoms consistently over a six-month period, yet 30 percent were considered at high risk for sexually transmitted diseases (STDs) because of multiple, sequential or concurrent relationships with male partners. The type of relationship in which the adolescents were involved did not predict consistency of condom use. Consistent condom use was associated with having asked a partner to use a condom, perceiving partner support for condom use, having less frequent sexual intercourse and using oral contraceptives inconsistently. The findings suggest that family planning providers need to more strongly emphasize to adolescents the importance of consistent condom use to protect against STD infection.

Implications of OSHA's reliance on TLVs in developing the air contaminants standard

This paper evaluates the decision by the Occupational Safety and Health Administration (OSHA) to base its Air Contaminants Standard on the threshold limit values (TLVs) of the American Conference of Governmental Industrial Hygienists. Contrary to the claim made by OSHA in promulgating the standard, the TLV list was not the sole available basis for a generic standard covering toxic air contaminants. The National Institute for Occupational Safety and Health (NIOSH) presented data indicating that the TLVs were insufficiently protective for 98 substances. NIOSH Recommended Exposure Limits (RELs) were available for 59 of these substances. The ratio of PEL to REL ranged up to 1,000, with a median of 2.5 and a mean of 71.4. OSHA excluded 42 substances from the standard altogether despite the availability of NIOSH RELs, solely because no TLV had been established.

Regulation of occupational carcinogens under OSHA's Air Contaminants Standard

We compare the information used by the Occupational Safety and Health Administration (OSHA) to regulate carcinogens under its 1989 Air Contaminants Standard to publicly available information on substances with potential carcinogenic activity. Carcinogenicity evaluations were obtained from the National Institute for Occupational Safety and Health (NIOSH), the American Conference of Governmental Industrial Hygienists (ACGIH), the National Toxicology Program (NTP), the Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IARC). We focus on three sets of substances: those which were regulated as carcinogens by OSHA in the Standard, those which were included in the Standard but whose exposure limits are based on noncarcinogenic effects, and those substances designated as potential carcinogens by NIOSH, ACGIH, and/or NTP but which were excluded from the Standard. The data indicate that OSHA relied almost exclusively upon the recommendations of the nongovernmental ACGIH to the exclusion of IARC and the three governmental bodies. Given their statutory authority to evaluate chemical carcinogenicity for regulatory agencies such as OSHA, the exclusion of NIOSH and NTP is particularly striking.

Evidence for exacerbation of irritable bowel syndrome during menses

Many women report that bowel symptoms are associated with menstruation, but neither the prevalence of these complaints nor their physiological basis is known. This study aimed to estimate prevalence, to determine whether patients with irritable bowel syndrome are more likely to make such complaints, and to determine whether bowel complaints during menstruation are attributable to psychological traits such as increased somatization. To estimate prevalence, 369 clients of Planned Parenthood of Maryland were asked whether gas, diarrhea, or constipation occurred during menstruation. These subjects were compared with women referred to a gastroenterology clinic and found to have irritable bowel syndrome or functional bowel disorder (abdominal pain plus altered bowel habits but not satisfying restrictive criteria for irritable bowel syndrome). Thirty-four percent of 233 Planned Parenthood clients who denied symptoms of irritable bowel syndrome or functional bowel disorder reported that menstruation was associated with one or more bowel symptoms. Gastroenterology clinic patients with irritable bowel syndrome were significantly more likely to experience exacerbations of each of these bowel symptoms, but especially increased bowel gas. Self-reports of bowel symptoms during menstruation were not associated with psychological traits or with menses-related changes in affect.