Early deaths in patients with heart failure discharged from the emergency department: a population-based analysis

BACKGROUND

Although approximately one third of patients with heart failure (HF) visiting the emergency department (ED) are discharged home, little is known about their care and outcomes.

METHODS AND RESULTS

We examined the acute care and early outcomes of patients with HF who visited an ED and were discharged without hospital admission in Ontario, Canada, from April 2004 to March 2007. Among 50 816 patients (age, 76.4+/-11.6 years; 49.4% men) visiting an ED for HF, 16 094 (31.7%) were discharged without hospital admission. A total of 4.0% died within 30 days from admission, and 1.3% died within 7 days of discharge from the ED. Although multiple (>or=2) previous HF admissions (odds ratio [OR], 1.64; 95% CI, 1.14 to 2.31), valvular heart disease (OR, 1.37; 95% CI, 1.00 to 1.84), peripheral vascular disease (OR, 1.41; 95% CI, 1.00 to 1.93), and respiratory disease (OR, 1.33; 95% CI, 1.08 to 1.63) increased the risk of 30-day death among those discharged from the ED, presence of these conditions did not increase the likelihood of admission. Patients were more likely to be admitted if they were older (OR, 1.08; 95% CI, 1.06 to 1.10 per decade), arrived by ambulance (OR, 2.02; 95% CI, 1.93 to 2.12), had a higher triage acuity score (OR, 4.12; 95% CI, 3.84 to 4.42), or received resuscitation in the ED (OR, 2.85; 95% CI, 2.68 to 3.04). In those with comparable predicted risks of death, subsequent 90-day mortality rates were higher among discharged than admitted patients (11.9% versus 9.5%; log-rank P=0.016).

CONCLUSIONS

Patients with HF who are discharged from the ED have substantial risks of early death, which, in some cases, may exceed that of hospitalized patients.

Association of blood pressure at hospital discharge with mortality in patients diagnosed with heart failure

BACKGROUND

Higher blood pressure in acute heart failure has been associated with improved survival; however, the relationship between blood pressure and survival in stabilized patients at hospital discharge has not been established.

METHODS AND RESULTS

In 7448 patients with heart failure (75.2+/-11.5 years; 49.9% men) discharged from the hospital in Ontario, Canada, we examined the association of systolic blood pressure (SBP) and diastolic blood pressure with long-term survival. Parametric survival analysis was performed, and survival time ratios were determined according to discharge blood pressure group. A total of 25 427 person-years of follow-up were examined. In those with left ventricular ejection fraction < or =40%, median survival was decreased by 17% (survival time ratio, 0.83; 95% CI, 0.71 to 0.98; P=0.029) when discharge SBP was 100 to 119 mm Hg and decreased by 23% (survival time ratio, 0.77; 95% CI, 0.62 to 0.97; P=0.024) when discharge SBP was <100 mm Hg, compared with those in the reference range of 120 to 139 mm Hg. Survival time ratios were 0.75 (95% CI, 0.60 to 0.92; P=0.007) and 0.75 (95% CI, 0.53 to 1.07; P=0.12) when discharge SBPs were 140 to 159 and > or =160 mm Hg, respectively. In those with left ventricular ejection fraction >40%, survival time ratios were 0.69 (95% CI, 0.51 to 0.93), 0.83 (95% CI, 0.71 to 0.99), 0.95 (95% CI, 0.80 to 1.14), and 0.76 (95% CI, 0.61 to 0.95) for discharge SBPs <100, 100 to 119, 140 to 159, and > or =160 mm Hg, respectively.

CONCLUSIONS

In this long-term population-based study of patients with heart failure, the association of discharge SBP with mortality followed a U-shaped distribution. Survival was shortened in those with reduced or increased values of discharge SBP.

"Dose-dependent" impact of recurrent cardiac events on mortality in patients with heart failure

BACKGROUND

The mortality impact of recurrent cardiac hospitalizations has not been delineated in community-based heart failure patients. We determined if a "dose-dependent" relationship exists between heart failure events and death, accounting for temporal changes in age, comorbidities, and disease severity.

METHODS

Among heart failure patients in the Enhanced Feedback For Effective Cardiac Treatment Study with onset between April 1999 and March 2001, we compared long-term survival (until March 2006) in those with recurrent heart failure or cardiovascular events, relative to those free of such events.

RESULTS

In 9138 patients, 28,442 person-years of follow-up were examined (mean age: 75.3 years, 49.6% male). Recurrent heart failure events occurred 1, 2, 3, and >or=4 times in 2352 (25.7%), 1020 (11.2%), 505 (5.5%), and 596 (6.5%) patients, respectively. Cardiovascular readmissions occurred 1, 2, 3, and >or=4 times in 2522 (27.6%), 1509 (16.5%), 975 (10.7%), and 1672 (18.3%) patients, respectively. Compared with those without recurrent heart failure events, the adjusted relative mortality rates for 1, 2, 3, and >or=4 heart failure events were 2.41 (95% confidence interval [CI], 2.24-2.60), 3.00 (95% CI 2.72-3.32), 4.00 (95% CI, 3.51-4.56), and 5.16 (95% CI, 4.55-5.85), respectively. Compared with those without cardiovascular events, the adjusted relative mortality rates for 1, 2, 3, and >or=4 cardiovascular events were 3.33 (95% CI, 3.05-3.63), 4.61 (95% CI, 4.16-5.10), 6.29 (95% CI, 5.59-7.07), and 8.95 (95% CI, 8.05-9.95), respectively.

CONCLUSIONS

The risk of death increases progressively and independently with each heart failure or cardiovascular event. The number of prior events predicts mortality and should be ascertained in patients with heart failure.

The effect of universal influenza immunization on mortality and health care use

BACKGROUND

In 2000, Ontario, Canada, initiated a universal influenza immunization program (UIIP) to provide free influenza vaccines for the entire population aged 6 mo or older. Influenza immunization increased more rapidly in younger age groups in Ontario compared to other Canadian provinces, which all maintained targeted immunization programs. We evaluated the effect of Ontario's UIIP on influenza-associated mortality, hospitalizations, emergency department (ED) use, and visits to doctors' offices.

METHODS AND FINDINGS

Mortality and hospitalization data from 1997 to 2004 for all ten Canadian provinces were obtained from national datasets. Physician billing claims for visits to EDs and doctors' offices were obtained from provincial administrative datasets for four provinces with comprehensive data. Since outcomes coded as influenza are known to underestimate the true burden of influenza, we studied more broadly defined conditions. Hospitalizations, ED use, doctors' office visits for pneumonia and influenza, and all-cause mortality from 1997 to 2004 were modelled using Poisson regression, controlling for age, sex, province, influenza surveillance data, and temporal trends, and used to estimate the expected baseline outcome rates in the absence of influenza activity. The primary outcome was then defined as influenza-associated events, or the difference between the observed events and the expected baseline events. Changes in influenza-associated outcome rates before and after UIIP introduction in Ontario were compared to the corresponding changes in other provinces. After UIIP introduction, influenza-associated mortality decreased more in Ontario (relative rate [RR] = 0.26) than in other provinces (RR = 0.43) (ratio of RRs = 0.61, p = 0.002). Similar differences between Ontario and other provinces were observed for influenza-associated hospitalizations (RR = 0.25 versus 0.44, ratio of RRs = 0.58, p < 0.001), ED use (RR = 0.31 versus 0.69, ratio of RRs = 0.45, p < 0.001), and doctors' office visits (RR = 0.21 versus 0.52, ratio of RRs = 0.41, p < 0.001). Sensitivity analyses were carried out to assess consistency, specificity, and the presence of a dose-response relationship. Limitations of this study include the ecological study design, the nonspecific outcomes, difficulty in modeling baseline events, data quality and availability, and the inability to control for potentially important confounders.

CONCLUSIONS

Compared to targeted programs in other provinces, introduction of universal vaccination in Ontario in 2000 was associated with relative reductions in influenza-associated mortality and health care use. The results of this large-scale natural experiment suggest that universal vaccination may be an effective public health measure for reducing the annual burden of influenza.

Effect of widespread restrictions on the use of hospital services during an outbreak of severe acute respiratory syndrome

BACKGROUND

Restrictions on the nonurgent use of hospital services were imposed in March 2003 to control an outbreak of severe acute respiratory syndrome (SARS) in Toronto, Ont. We describe the impact of these restrictions on health care utilization and suggest lessons for future epidemics.

METHODS

We performed a retrospective population-based study of the Greater Toronto Area (hereafter referred to as Toronto) and unaffected comparison regions (Ottawa and London, Ont.) before, during and after the SARS outbreak (April 2001-March 2004). We determined the adjusted rates of hospital admissions, emergency department and outpatient visits, diagnostic testing and drug prescribing.

RESULTS

During the early and late SARS restriction periods, the rate of overall and medical admissions decreased by 10%-12% in Toronto; there was no change in the comparison regions. The rate of elective surgery in Toronto fell by 22% and 15% during the early and late restriction periods respectively and by 8% in the comparison regions. The admission rates for urgent surgery remained unchanged in all regions; those for some acute serious medical conditions decreased by 15%-21%. The rates of elective cardiac procedures declined by up to 66% in Toronto and by 71% in the comparison regions; the rates of urgent and semi-urgent procedures declined little or increased. High-acuity visits to emergency departments fell by 37% in Toronto, and inter-hospital patient transfers fell by 44% in the circum-Toronto area. Drug prescribing and primary care visits were unchanged in all regions.

INTERPRETATION

The restrictions achieved modest reductions in overall hospital admissions and substantial reductions in the use of elective services. Brief reductions occurred in admissions for some acute serious conditions, high-acuity visits to emergency departments and inter-hospital patient transfers suggesting that access to care for some potentially seriously ill patients was affected.

Analysis of observational studies in the presence of treatment selection bias: effects of invasive cardiac management on AMI survival using propensity score and instrumental variable methods

CONTEXT

Comparisons of outcomes between patients treated and untreated in observational studies may be biased due to differences in patient prognosis between groups, often because of unobserved treatment selection biases.

OBJECTIVE

To compare 4 analytic methods for removing the effects of selection bias in observational studies: multivariable model risk adjustment, propensity score risk adjustment, propensity-based matching, and instrumental variable analysis.

DESIGN, SETTING, AND PATIENTS

A national cohort of 122,124 patients who were elderly (aged 65-84 years), receiving Medicare, and hospitalized with acute myocardial infarction (AMI) in 1994-1995, and who were eligible for cardiac catheterization. Baseline chart reviews were taken from the Cooperative Cardiovascular Project and linked to Medicare health administrative data to provide a rich set of prognostic variables. Patients were followed up for 7 years through December 31, 2001, to assess the association between long-term survival and cardiac catheterization within 30 days of hospital admission.

MAIN OUTCOME MEASURE

Risk-adjusted relative mortality rate using each of the analytic methods.

RESULTS

Patients who received cardiac catheterization (n = 73 238) were younger and had lower AMI severity than those who did not. After adjustment for prognostic factors by using standard statistical risk-adjustment methods, cardiac catheterization was associated with a 50% relative decrease in mortality (for multivariable model risk adjustment: adjusted relative risk [RR], 0.51; 95% confidence interval [CI], 0.50-0.52; for propensity score risk adjustment: adjusted RR, 0.54; 95% CI, 0.53-0.55; and for propensity-based matching: adjusted RR, 0.54; 95% CI, 0.52-0.56). Using regional catheterization rate as an instrument, instrumental variable analysis showed a 16% relative decrease in mortality (adjusted RR, 0.84; 95% CI, 0.79-0.90). The survival benefits of routine invasive care from randomized clinical trials are between 8% and 21%.

CONCLUSIONS

Estimates of the observational association of cardiac catheterization with long-term AMI mortality are highly sensitive to analytic method. All standard risk-adjustment methods have the same limitations regarding removal of unmeasured treatment selection biases. Compared with standard modeling, instrumental variable analysis may produce less biased estimates of treatment effects, but is more suited to answering policy questions than specific clinical questions.

Appropriate measures of influenza immunization program effectiveness

Groll and Thomson's evaluation of the effectiveness of Ontario's Universal Influenza Immunization Campaign used per capita cases of laboratory-confirmed influenza. We argue that these data are susceptible to various biases and should not be used as an outcome measure. Laboratory data are traditionally used to identify the presence of influenza activity rather than to identify levels of influenza activity. A better measure of viral activity is the proportion of influenza tests positive; whereas the weekly proportion of tests positive was relatively consistent, a marked increase over time in the numbers of laboratory-confirmed cases paralleled an increase in the number of tests performed. Regardless, for evaluating universal influenza immunization program effectiveness, other established and available measures employed in previous studies describing the epidemiology of influenza should be used instead of laboratory data.

Hospital volume and mortality for mechanical ventilation of medical and surgical patients: A population-based analysis using administrative data*

OBJECTIVE

In an effort to improve efficiency and quality of care, regionalization of adult critical care services, similar to trauma and neonatal intensive care, has been suggested. However, there is little research to understand if hospitals with higher patient volumes have better outcomes. Our objective is to determine whether hospital volume is associated with improved survival for medical or surgical patients receiving mechanical ventilation.

DESIGN

Population-based retrospective cohort study.

SETTING

Province of Ontario, Canada.

PATIENTS

A total of 13,846 medical and 6,373 surgical patients receiving mechanical ventilation for greater than two consecutive days between 1998 and 2000.

INTERVENTIONS

None.

MEASUREMENTS

Odds ratio for death within 30 days of initiation of mechanical ventilation was calculated in relation to hospital volume of ventilation. Estimates were adjusted for patient demographics, diagnoses, and urgency status; hospital region and rural location; and accounted for clustering within hospitals.

MAIN RESULTS

There was no effect of volume on mortality for surgical patients. After adjustment for clustering, among medical patients, the lowest-volume category (<100 episodes/yr) had a nonsignificant increase in mortality, with an odds ratio (95% confidence interval) of 1.13 (0.87-1.47) compared with the highest-volume category (> or =700 episodes/yr). A post hoc analysis revealed that within the lowest-volume category, the proportion of patients transferred to larger hospitals was 81% for hospitals with <20 episodes/yr and only 32% for hospitals with 20-99 episodes/yr, with odds ratios (95% confidence interval) for mortality of 0.74 (0.49-1.12) and 1.18 (0.90-1.54), respectively, compared with the highest-volume category.

CONCLUSIONS

For surgical patients requiring mechanical ventilation for >2 days, hospital volume had no effect on mortality. For medical patients, higher mortality may occur in a subgroup of low-volume hospitals that do not routinely transfer their patients to larger-volume facilities. This finding needs further investigation in a larger-sized study.

The effect of universal influenza immunization on vaccination rates in Ontario

OBJECTIVES

This article examines the association between introduction of Ontario's Universal Influenza Immunization Program and changes in vaccination rates over time in Ontario, compared with the other provinces combined.

DATA SOURCES

The data are from the 1996/97 National Population Health Survey and the 2000/01 and 2003 Canadian Community Health Survey, both conducted by Statistics Canada.

ANALYTICAL TECHNIQUES

Cross-tabulations were used to estimate vaccination rates for the total population aged 12 or older, for groups especially vulnerable to the effects of influenza, and by selected socio-demographic variables. Z tests and multiple logistic regression were used to examine differences between estimates.

MAIN RESULTS

Between 1996/97 and 2000/01, the increase in the overall vaccination rate in Ontario was 10 percentage points greater than the increase in the other provinces combined. Increases in Ontario were particularly pronounced among people who were: younger than 65, more educated, and had a higher household income. Between 2000/01 and 2003, vaccination rates were stable in Ontario, while rates continued to rise in the other provinces. Even so, Ontario's 2003 rates exceeded those in the other provinces.

End-Of-Life Care At Academic Medical Centers: Implications For Future Workforce Requirements

The expansion of U.S. physician workforce training has been justified on the basis of population growth, technological innovation, and economic expansion. Our analyses found threefold differences in physician full-time-equivalent (FTE) inputs for Medicare cohorts cared for at academic medical centers (AMCs); AMC inputs were highly correlated with the number of physician FTEs per Medicare beneficiary in AMC regions. Given the apparent inefficiency of current physician practices, the supply pipeline is sufficient to meet future needs through 2020, with adoption of the workforce deployment patterns now seen among AMCs and regions dominated by large group practices.

How are volume-outcome associations related to models of health care funding and delivery? A comparison of the United States and Canada

How models of health care financing and delivery affect patterns of procedure volumes, outcomes, and volume-outcome associations is not known. We compared volume-outcome studies done in Canada, which provides residents with universal, single-payer health care, with those done in the United States, to determine whether there was a difference in the likelihood of finding statistically significant volume-outcome associations. We analyzed 142 articles, most (90.1%) of which were from the United States. The articles described a total of 291 separate analyses. After adjusting for the clustering of multiple analyses in the same study, the likelihood of finding a statistically significant volume-outcome association was substantially lower in Canadian studies as compared with those from the United States (odds ratio 0.24, 95% confidence interval 0.08 to 0.74, p = 0.01). This result persisted after adjustment for the procedure/condition studied, and the number of study subjects. Canadian volume-outcome analyses are less likely to identify statistically significant volume-outcome associations than US studies, possibly because of the smaller size of some Canadian studies. It is also possible that different models of health care financing and delivery affect patterns of procedure volumes and volume-outcome associations. By promoting competition between hospitals and providers, market-based models may exacerbate existing variations in the quality of hospital care.

Regional variation in rates of low birth weight

OBJECTIVE

Low birth weight (LBW; < 2500 g) is the result of complex and poorly understood interactions between the biological determinants of the mother and the fetus, the parent's socioeconomic status, and medical care. After controlling for these established risk factors, the extent of regional variation in LBW rates remains unknown. This study measures regional variation in LBW rates and identifies regions of neonatal health services with significantly high or low adjusted rates.

METHODS

Linking the United States 1998 singleton birth cohort (N = 3.8 million) with county and health care characteristics, we conducted a small area analysis of LBW across 246 regions of neonatal health services. We measured observed rates and then used a multivariable, hierarchical model to estimate adjusted LBW rates by regions. We then stratified these rates by race for the 208 regions with adequate sample size.

RESULTS

Observed LBW rates varied across regions from 3.8 to 10.6 per 100 live births (interquartile range: 5.0-6.8 [25th-75th percentile]; median: 5.9). After controlling for known maternal and area risk factors, 67 (27.0%) regions had rates significantly below and 98 (39.8%) regions had rates significantly higher than the national rate of 6.0 per 100 live births. Although black mothers were more likely to give birth to an LBW newborn, regional adjusted rates still varied > 3-fold within both black and nonblack subgroups.

CONCLUSIONS

After controlling for known maternal and area risk factors, LBW rates markedly varied across US regions of neonatal health services for both black and nonblack mothers. Additional analyses of these regions may provide opportunities for regional accountability in pregnancy outcomes, LBW research, and targeted improvement interventions, especially in high-risk populations.

Rate of elective cholecystectomy and the incidence of severe gallstone disease

BACKGROUND

The use of elective cholecystectomy has increased dramatically following the widespread adoption of laparoscopic cholecystectomy. We sought to determine whether this increase has resulted in a reduction in the incidence of severe complications of gallstone disease.

METHODS

We examined longitudinal trends in the population-based rates of severe gallstone disease from 1988 to 2000, using a quasi-experimental longitudinal design to assess the effects of the large increase in elective cholecystectomy rates after 1991 among people aged 18 years and older residing in Ontario. We also measured the rate of hospital admission because of acute diverticulitis, to control for secular trends in the use of hospital care for acute abdominal diseases.

RESULTS

The adjusted annual rate of elective cholecystectomy per 100,000 population increased from 201.3 (95% confidence interval [CI] 197.0-205.8) in 1988-1990 to 260.8 (95% CI 257.1- 264.5) in 1992-2000 (rate ratio [RR] 1.35, 95% CI 1.32- 1.38, p 0.001). An anomalously high number of elective cholecystectomies were performed in 1991. Overall, the annual rate of severe gallstone diseases (acute cholecystitis, acute biliary pancreatitis and acute cholangitis) declined by 10% (RR 0.90, 95% CI 0.88- 0.91) for 1992-2000 as compared with 1988-1991. This decline was entirely due to an 18% reduction in the rate of acute cholecystitis (RR 0.82, 95% CI 0.80-0.84).

INTERPRETATION

The increase in the rate of elective cholecystectomy that occurred following the introduction of laparoscopic cholecystectomy in 1991 was associated with an overall reduction in the incidence of severe gallstone disease that was entirely attributable to a reduction in the incidence of acute cholecystitis.

Use of Medicare claims data to monitor provider-specific performance among patients with severe chronic illness

This study illustrates that Medicare claims can be used to measure population-based, provider-specific rates of resource inputs, utilization, and Medicare spending. The target populations are seventy-seven cohorts of chronically ill Medicare enrollees who received most of their care from seventy-seven well-known U.S. hospitals. Striking variations are documented in resource inputs and use of services during the last six months of life. The patterns of care seen in the progression of chronic illness correlate highly with care received during previous periods. We believe that hospital-specific measures can be helpful in identifying providers with acceptable quality indices who are also relatively efficient in managing chronic illness.

Use of hospitals, physician visits, and hospice care during last six months of life among cohorts loyal to highly respected hospitals in the United States

OBJECTIVE

To evaluate the use of healthcare resources during the last six months of life among patients of US hospitals with strong reputations for high quality care in managing chronic illness.

DESIGN

Retrospective cohort study based on claims data from the US Medicare programme.

PARTICIPANTS

Cohorts receiving most of their hospital care from 77 hospitals that appeared on the 2001 US News and World Report "best hospitals" list for heart and pulmonary disease, cancer, and geriatric services.

MAIN OUTCOME MEASURES

Use of healthcare resources in the last six months of life: number of days spent in hospital and in intensive care units; number of physician visits; percentage of patients seeing 10 or more physicians; percentage enrolled in hospice. Terminal care: percentage of deaths occurring in hospital; percentage of deaths occurring in association with a stay in an intensive care unit.

RESULTS

Extensive variation in each measure existed among the 77 hospital cohorts. Days in hospital per decedent ranged from 9.4 to 27.1 (interquartile range 11.6-16.1); days in intensive care units ranged from 1.6 to 9.5 (2.6-4.5); number of physician visits ranged from 17.6 to 76.2 (25.5-39.5); percentage of patients seeing 10 or more physicians ranged from 16.9% to 58.5% (29.4-43.4%); and hospice enrollment ranged from 10.8% to 43.8% (22.0-32.0%). The percentage of deaths occurring in hospital ranged from 15.9% to 55.6% (35.4-43.1%), and the percentage of deaths associated with a stay in intensive care ranged from 8.4% to 36.8% (20.2-27.1%).

CONCLUSION

Striking variation exists in the utilisation of end of life care among US medical centres with strong national reputations for clinical care.

Variations In The Longitudinal Efficiency Of Academic Medical Centers

Recent studies have revealed dramatic differences among academic medical centers (AMCs) in the quantity of care provided to their patients. The implications, however, depend upon whether the additional resources provided by some centers lead to better results. This study describes the content, quality, and outcomes of care across AMCs that differ by up to 60 percent in the overall intensity of medical services delivered to patients with serious chronic illnesses. Efforts to reduce costs will require attention to supply-sensitive services (the frequency of hospital stays, physician visits, specialist consultations, diagnostic tests, and minor procedures) and should include a focus on the longitudinal efficiency of hospitals and medical staffs.

The implications of regional variations in Medicare spending. Part 1: the content, quality, and accessibility of care

BACKGROUND

The health implications of regional differences in Medicare spending are unknown.

OBJECTIVE

To determine whether regions with higher Medicare spending provide better care.

DESIGN

Cohort study.

SETTING

National study of Medicare beneficiaries.

PATIENTS

Patients hospitalized between 1993 and 1995 for hip fracture (n = 614,503), colorectal cancer (n = 195,429), or acute myocardial infarction (n = 159,393) and a representative sample (n = 18,190) drawn from the Medicare Current Beneficiary Survey (1992-1995). EXPOSURE MEASUREMENT: End-of-life spending reflects the component of regional variation in Medicare spending that is unrelated to regional differences in illness. Each cohort member's exposure to different levels of spending was therefore defined by the level of end-of-life spending in his or her hospital referral region of residence (n = 306).

OUTCOME MEASUREMENTS

Content of care (for example, frequency and type of services received), quality of care (for example, use of aspirin after acute myocardial infarction, influenza immunization), and access to care (for example, having a usual source of care).

RESULTS

Average baseline health status of cohort members was similar across regions of differing spending levels, but patients in higher-spending regions received approximately 60% more care. The increased utilization was explained by more frequent physician visits, especially in the inpatient setting (rate ratios in the highest vs. the lowest quintile of hospital referral regions were 2.13 [95% CI, 2.12 to 2.14] for inpatient visits and 2.36 [CI, 2.33 to 2.39] for new inpatient consultations), more frequent tests and minor (but not major) procedures, and increased use of specialists and hospitals (rate ratio in the highest vs. the lowest quintile was 1.52 [CI, 1.50 to 1.54] for inpatient days and 1.55 [CI, 1.50 to 1.60] for intensive care unit days). Quality of care in higher-spending regions was no better on most measures and was worse for several preventive care measures. Access to care in higher-spending regions was also no better or worse.

CONCLUSIONS

Regional differences in Medicare spending are largely explained by the more inpatient-based and specialist-oriented pattern of practice observed in high-spending regions. Neither quality of care nor access to care appear to be better for Medicare enrollees in higher-spending regions.

The implications of regional variations in Medicare spending. Part 2: health outcomes and satisfaction with care

BACKGROUND

The health implications of regional differences in Medicare spending are unknown.

OBJECTIVE

To determine whether regions with higher Medicare spending achieve better survival, functional status, or satisfaction with care.

DESIGN

Cohort study.

SETTING

National study of Medicare beneficiaries.

PATIENTS

Patients hospitalized between 1993 and 1995 for hip fracture (n = 614,503), colorectal cancer (n = 195,429), or acute myocardial infarction (n = 159,393) and a representative sample (n = 18,190) drawn from the Medicare Current Beneficiary Survey (MCBS) (1992-1995). EXPOSURE MEASUREMENT: End-of-life spending reflects the component of regional variation in Medicare spending that is unrelated to regional differences in illness. Each cohort member's exposure to different levels of spending was therefore defined by the level of end-of-life spending in his or her hospital referral region of residence (n = 306).

OUTCOME MEASUREMENTS

5-year mortality rate (all four cohorts), change in functional status (MCBS cohort), and satisfaction (MCBS cohort).

RESULTS

Cohort members were similar in baseline health status, but those in regions with higher end-of-life spending received 60% more care. Each 10% increase in regional end-of-life spending was associated with the following relative risks for death: hip fracture cohort, 1.003 (95% CI, 0.999 to 1.006); colorectal cancer cohort, 1.012 (CI, 1.004 to 1.019); acute myocardial infarction cohort, 1.007 (CI, 1.001 to 1.014); and MCBS cohort, 1.01 (CI, 0.99 to 1.03). There were no differences in the rate of decline in functional status across spending levels and no consistent differences in satisfaction.

CONCLUSIONS

Medicare enrollees in higher-spending regions receive more care than those in lower-spending regions but do not have better health outcomes or satisfaction with care. Efforts to reduce spending should proceed with caution, but policies to better manage further spending growth are warranted.

The relation between the availability of neonatal intensive care and neonatal mortality

BACKGROUND

There is marked regional variation in the availability of neonatal intensive care in the United States. We conducted a study to determine whether a greater supply of neonatologists or neonatal intensive care beds is associated with lower neonatal mortality.

METHODS

We used the 1996 master files of the American Medical Association and the American Osteopathic Association and 1998 and 1999 surveys of neonatal intensive care units to calculate the supply of neonatologists and neonatal intensive care beds in 246 neonatal intensive care regions. We used linked birth and death records from the 1995 U.S. birth cohort to assess associations between the supply of both neonatologists and neonatal intensive care beds per capita (in quintiles) and the risk of death within the first 27 days of life.

RESULTS

Among 3,892,208 newborns with a birth weight of 500 g or greater, the mortality rate was 3.4 per 1000 births. After adjustment for neonatal and maternal characteristics associated with an increased risk of neonatal death, the rate was lower in the regions with 4.3 neonatologists per 10,000 births than in those with 2.7 neonatologists per 10,000 births (odds ratio for death, 0.93; 95 percent confidence interval, 0.88 to 0.99). Further increases in the number of neonatologists were not associated with greater reductions in the risk of death. There was no consistent relation between the number of neonatal intensive care beds and neonatal mortality.

CONCLUSIONS

A minority of regions in the United States may have inadequate neonatal intensive care resources, whereas many others may have more resources than are needed to prevent the death of high-risk newborns. The effect of the availability of neonatologists on other health outcomes is not known.

A pooled analysis of 10 case-control studies of melanoma and oral contraceptive use

Data regarding the effects of oral contraceptive use on women's risk of melanoma have been difficult to resolve. We undertook a pooled analysis of all case-control studies of melanoma in women completed as of July 1994 for which electronic data were available on oral contraceptive use along with other melanoma risk factors such as hair colour, sun sensitivity, family history of melanoma and sun exposure. Using the original data from each investigation (a total of 2391 cases and 3199 controls), we combined the study-specific odds ratios and standard errors to obtain a pooled estimate that incorporates inter-study heterogeneity. Overall, we observed no excess risk associated with oral contraceptive use for 1 year or longer compared to never use or use for less than 1 year (pooled odds ratio (pOR)=0.86; 95% CI=0.74-1.01), and there was no evidence of heterogeneity between studies. We found no relation between melanoma incidence and duration of oral contraceptive use, age began, year of use, years since first use or last use, or specifically current oral contraceptive use. In aggregate, our findings do not suggest a major role of oral contraceptive use on women's risk of melanoma.

Are neonatal intensive care resources located according to need? Regional variation in neonatologists, beds, and low birth weight newborns

OBJECTIVE

Despite marked growth in neonatal intensive care during the past 30 years, it is not known if neonatologists and beds are preferentially located in regions with greater newborn risk. This study reports the relationship between regional measures of intensive care capacity and low birth weight infants using newly developed market-based regions of neonatal intensive care.

DESIGN

Cross-sectional small-area analysis of 246 neonatal intensive care regions (NICRs).

DATA SOURCES

1996 American Medical Association and American Osteopathic Association masterfiles data of clinically active neonatologists; 1999 American Academy of Pediatrics Section on Perinatal Pediatrics survey of directors of neonatal intensive care units in the United States with 100% response rate; 1995 linked birth/death data.

RESULTS

The number of total births per neonatologist across NICRs ranged from 390 to 8197 (median: 1722) and the number of total births per intensive care bed ranged from 72 to 1319 (median: 317). The associations between capacity measures and low birth weight rates across NICRs were statistically significant but negligible (R(2): 0.04 for neonatologists; 0.05 for beds). NICRs in the quintile with the greatest neonatologist capacity (average of only 863 births per neonatologist) had very low birth weight (VLBW) rates of 1.5% while those in the quintile of lowest neonatologist capacity (average of 3718 births per neonatologist) had VLBW rates of 1.3%; a similar lack of meaningful difference in VLBW rates was noted across quintiles of intensive care bed capacity. Including midlevel providers and intermediate care beds to the analyses did not alter the findings.

CONCLUSIONS

Neonatal intensive care capacity is not preferentially located in regions with greater newborn need as measured by low birth weight rates. Whether greater capacity affords benefits to the newborns remains unknown.

Two-stage methods for the analysis of pooled data

Epidemiologic studies of disease often produce inconclusive or contradictory results due to small sample sizes or regional variations in the disease incidence or the exposures. To clarify these issues, researchers occasionally pool and reanalyse original data from several large studies. In this paper we explore the use of a two-stage random-effects model for analysing pooled case-control studies and undertake a thorough examination of bias in the pooled estimator under various conditions. The two-stage model analyses each study using the model appropriate to the design with study-specific confounders, and combines the individual study-specific adjusted log-odds ratios using a linear mixed-effects model; it is computationally simple and can incorporate study-level covariates and random effects. Simulations indicate that when the individual studies are large, two-stage methods produce nearly unbiased exposure estimates and standard errors of the exposure estimates from a generalized linear mixed model. By contrast, joint fixed-effects logistic regression produces attenuated exposure estimates and underestimates the standard error when heterogeneity is present. While bias in the pooled regression coefficient increases with interstudy heterogeneity for both models, it is much smaller using the two-stage model. In pooled analyses, where covariates may not be uniformly defined and coded across studies, and occasionally not measured in all studies, a joint model is often not feasible. The two-stage method is shown to be a simple, valid and practical method for the analysis of pooled binary data. The results are applied to a study of reproductive history and cutaneous melanoma risk in women using data from ten large case-control studies.

Panel-based pain management in primary care. a pilot study

Although pain is an extremely common symptom presenting to primary care physicians, it frequently is not optimally managed. The purpose of this feasibility study was to develop and pilot-test an efficient, rapid assessment and management approach for pain in busy community practices. The intervention utilized the Dartmouth COOP Clinical Improvement System (DCCIS) and a telephone-based, nurse-educator intervention. Patients from four primary care practices in rural New Hampshire and Vermont were screened by mail for the presence of persistent pain. Patients with mild to severe pain were randomized to either the usual care control group (n = 383) or the intervention group (n = 320). Patients who reported pain but no psychosocial problems received a summary of identified problems and targeted educational material via mail (DCCIS). Patients who reported pain and psychosocial problems received the DCCIS intervention and calls from a nurse-educator who provided pain self-management strategies and a problem-solving approach for psychosocial problems. Post-treatment evaluation revealed that patients in the intervention group scored significantly better on the Pain, Physical, Emotional, and Social subscales of the SF-36 and on the total score of the Functional Interference Scale, as compared to a usual care control group. Feasibility and acceptability of the approach were demonstrated; however, the conclusions based on analyses of the post-treatment outcomes were tempered by baseline imbalances across groups.

The uneven landscape of newborn intensive care services: variation in the neonatology workforce

CONTEXT

In the past 30 years, the number of neonatologists has increased while total births have remained nearly constant. It is not known how equitably this expanded workforce is distributed.

OBJECTIVE

To determine the geographic distribution of neonatologists in the United States.

DATA SOURCES

1996 American Medical Association physician masterfiles; 1999 survey of all U.S. neonatal intensive care units; 1995 American Hospital Association hospital survey; and 1995 U.S. vital records.

MEASURES

The number of neonatologists and neonatal mid-level providers per live birth within 246 market-based regions.

RESULTS

The neonatology workforce varied substantially across neonatal intensive care regions. The number of neonatologists per 10,000 live births ranged from 1.2 to 25.6 with an interquintile range of 3.5 to 8.5. The weakly positive correlation between neonatologists and neonatal mid-level providers per live birth is not consistent with substitution of neonatal mid-level providers for neonatologists (Spearman rank-correlation coefficient, 0.17; P < 0.01). There was no difference in the percentage of neonatal fellows in the lowest and highest workforce quintile (14% vs. 16%) or in the percentage of neonatologists engaged predominantly in research, teaching, or administration (14% in lowest and highest quintiles).

CONCLUSIONS

The regional supply of neonatologists varies dramatically and cannot be explained by the substitution of neonatal mid-level providers or by the presence of academic medical centers. Further research is warranted to understand whether neonatal intensive care resources are located in accordance with risk and whether more resources improve newborn outcomes.

Skin cancer risk in relation to toenail arsenic concentrations in a US population-based case-control study

Arsenic is a known carcinogen specifically linked to skin cancer occurrence in regions with highly contaminated drinking water or in individuals who took arsenic-containing medicines. Presently, it is unknown whether such effects occur at environmental levels found in the United States. To address this question, the authors used data collected on 587 basal cell and 284 squamous cell skin cancer cases and 524 controls interviewed as part of a case-control study conducted in New Hampshire between 1993 and 1996. Arsenic was determined in toenail clippings using instrumental neutron activation analysis. The odds ratios for squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) were close to unity in all but the highest category. Among individuals with toenail arsenic concentrations above the 97th percentile, the adjusted odds ratios were 2.07 (95% confidence interval (CI): 0.92, 4.66) for SCC and 1.44 (95% CI: 0.74, 2.81) for BCC, compared with those with concentrations at or below the median. While the risks of SCC and BCC did not appear elevated at the toenail arsenic concentrations detected in most study subjects, the authors cannot exclude the possibility of a dose-related increase at the highest levels of exposure experienced in the New Hampshire population.

Therapeutic ionizing radiation and the incidence of basal cell carcinoma and squamous cell carcinoma. The New Hampshire Skin Cancer Study Group

OBJECTIVE

To estimate the relative risk of developing basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) after receiving therapeutic ionizing radiation.

DESIGN

Population-based case-control study.

SETTING

New Hampshire.

PATIENTS

A total of 592 cases of BCC and 289 cases of SCC identified through a statewide surveillance system and 536 age- and sex-matched controls selected from population lists.

MAIN OUTCOME MEASURES

Histologically confirmed BCC and invasive SCC diagnosed between July 1, 1993, through June 30, 1995, among New Hampshire residents.

RESULTS

Information regarding radiotherapy and other factors was obtained through personal interviews. An attempt was made to review the radiation treatment records of subjects who reported a history of radiotherapy. Overall, an increased risk of both BCC and SCC was found in relation to therapeutic ionizing radiation. Elevated risks were confined to the site of radiation exposure (BCC odds ratio, 3. 30; 95% confidence interval, 1.60-6.81; SCC odds ratio, 2.94; 95% confidence interval, 1.30-6.67) and were most pronounced for those irradiated for acne exposure. For SCC, an association with radiotherapy was observed only among those whose skin was likely to sunburn with sun exposure.

CONCLUSIONS

These results largely agree with those of previous studies on the risk of BCC in relation to ionizing radiation exposure. In addition, they suggest that the risk of SCC may be increased by radiotherapy, especially in individuals prone to sunburn with sun exposure. Arch Dermatol. 2000;136:1007-1011

Associations among hospital capacity, utilization, and mortality of US Medicare beneficiaries, controlling for sociodemographic factors

OBJECTIVE

To explore whether geographic variations in Medicare hospital utilization rates are due to differences in local hospital capacity, after controlling for socioeconomic status and disease burden, and to determine whether greater hospital capacity is associated with lower Medicare mortality rates.

DATA SOURCES/STUDY SETTING

The study population: a 20 percent sample of 1989 Medicare enrollees. Measures of resources were based on a national small area analysis of 313 Hospital Referral Regions (HRR). Demographic and socioeconomic data were obtained from the 1990 U.S. Census. Measures of local disease burden were developed using Medicare claims files.

STUDY DESIGN

The study was a cross-sectional analysis of the relationship between per capita measures of hospital resources in each region and hospital utilization and mortality rates among Medicare enrollees. Regression techniques were used to control for differences in sociodemographic characteristics and disease burden across areas.

DATA COLLECTION/EXTRACTION METHODS

Data on the study population were obtained from Medicare enrollment (Denominator File) and hospital claims files (MedPAR) and U.S. Census files.

PRINCIPAL FINDINGS

The per capita supply of hospital beds varied by more than twofold across U.S. regions. Residents of areas with more beds were up to 30 percent more likely to be hospitalized, controlling for ecologic measures of socioeconomic characteristics and disease burden. A greater proportion of the population was hospitalized at least once during the year in areas with more beds; death was also more likely to take place in an inpatient setting. All effects were consistent across racial and income groups. Residence in areas with greater levels of hospital resources was not associated with a decreased risk of death.

CONCLUSIONS

Residence in areas of greater hospital capacity is associated with substantially increased use of the hospital, even after controlling for socioeconomic characteristics and illness burden. This increased use provides no detectable mortality benefit.

Has asthma medication use in children become more frequent, more appropriate, or both?

OBJECTIVE

Despite national initiatives to improve asthma medical treatment, the appropriateness of physician prescribing for children with asthma remains unknown. This study measures trends and recent patterns in the pediatric use of medications approved for reversible obstructive airway disease (asthma medications).

DESIGN

Population-based longitudinal and cross-sectional analyses. Setting. A nonprofit staff model health maintenance organization located in the Puget Sound area of Washington state.

PARTICIPANTS

Children 0 to 17 years of age enrolled continuously during any one of the years from 1984 to 1993 (N = 83 232 in 1993). PRIMARY OUTCOME MEASURES. Percent of enrollees filling prescriptions for asthma medications and fill rates by medication class and estimated duration of inhaled antiinflammatory medication use.

RESULTS

Between 1984 and 1993, the frequency of asthma medication use increased: the percent of children filling any asthma medication prescription increased from 4. 0% to 8.1%, whereas the percent filling an inhaled antiinflammatory inhaler rose from 0.4% to 2.4%. In contrast, the intensity of inhaled antiinflammatory use decreased among users; 37% of users filled more than two inhalers during the year in 1984, and 29% in 1993. In high beta-agonist users (filling more than two beta-agonist inhalers each quarter per year), the estimated duration of inhaled antiinflammatory use increased slightly from a mean of 4.1 months per year in 1984-1986 to 5.0 months in 1991-1993; estimated duration of use in adolescents 10 to 17 years of age was approximately half that of children 5 to 9 years of age.

CONCLUSIONS

The proportion of children using asthma medications increased substantially during the study period, but the use of inhaled antiinflammatory medication per patient remained low even for those using large amounts of inhaled beta-agonists. These findings suggest that most asthma medications were used by children with mild lower airway symptoms and that inhaled antiinflammatory medication use in children with more severe disease fell short of national guidelines.

Increase in incidence rates of basal cell and squamous cell skin cancer in New Hampshire, USA. New Hampshire Skin Cancer Study Group

We conducted a study to estimate the current incidence rates of basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC) of the skin in the population of New Hampshire (NH), USA, and to quantify recent changes in the incidence rates of these malignancies. BCCs and SCCs diagnosed among NH residents were identified through physician practices and central pathology laboratories in NH and bordering regions from June 1979 through May 1980 and from July 1993 through June 1994. For each diagnosis period, we estimated the age-adjusted incidence rates for both BCC and SCC among both men and women and for separate anatomic sites. Between 1979-1980 and 1993-1994, incidence rates of SCC increased by 235% in men and by 350% in women. Incidence rates of BCC increased by more than 80% in both men and women. While the absolute increase was greatest for tumors of the head and neck, the relative change was most pronounced for tumors on the trunk in men and on the lower limb in women. Thus, there has been a marked rise in the incidence rates of BCC and SCC skin cancers in NH in recent years. The anatomic pattern of increase in BCC and SCC incidence is consistent with an effect of greater sunlight exposure. Studies of BCC and SCC occurrence are needed to identify possible behavioral and environmental factors and to assess possible changes in diagnostic practices that might account for the rise in incidence of these common malignancies.

A randomized trial of the use of patient self-assessment data to improve community practices

OBJECTIVE

Because of time constraints in the office environment, problems of concern to elderly patients may not be raised during clinic visits. To facilitate communication about geriatric health problems, we examined the impact of a strategy that used patient self-assessment data to improve community practices.

DESIGN

Twenty-two primary care practices were randomized to participate in the intervention strategy (intervention practices) or to provide usual care (usual care practices).

SETTING

Primary care practices in 16 towns in New Hampshire (total, 45 physicians).

PATIENTS

1651 patients 70 years of age or older.

INTERVENTION

All patients received a mailed survey that asked about their health problems and about how well these problems were being addressed by their physicians. In the intervention practices, these data were used to generate a customized letter that directed the patient to specific sections in an 80-page modified version of the National Institute on Aging's Age Pages and were summarized and communicated to the patient's physician.

MAIN OUTCOME MEASURE

Change from baseline in patients' overall assessment of health care.

RESULTS

In 8 of 11 intervention practices, patients felt that their care had improved over the 2-year study period. This improvement occurred in only 1 of 11 usual care practices (P = 0.003). Patients in intervention practices reported receiving significantly more help with physical function, fall prevention, and assistance for memory problems. Self-assessed health status did not differ in the two groups.

CONCLUSION

A standard, easy-to-implement strategy to improve the quality of provider--patient interactions can improve the satisfaction of older patients cared for in community practices.

Physical symptom trajectories following trauma exposure: longitudinal findings from the normative aging study

This study modeled physical symptom trajectories from ages 30 to 75 in 1079 older male military veterans who were assessed every 3 to 5 years since the 1960s. Combat exposure and noncombat trauma were used to define four groups: no trauma (N = 249), noncombat trauma only (N = 333), combat only (N = 152), and both combat and noncombat trauma (N = 345). Number of symptoms on the Cornell Medical Index physical symptom scale increased 29% per decade. Men who had experienced either combat or noncombat trauma did not differ from nonexposed men, but those who had experienced both combat and noncombat trauma had 16% more symptoms across all ages. There were no differences in age-related trajectories as a function of trauma history. In cross-sectional analysis, men with combat and noncombat trauma had more posttraumatic stress disorder symptoms, but not more depression symptoms, than men with either no trauma or noncombat trauma only. Discussion focuses on the importance of considering physical as well as psychological outcomes of exposure to traumatic events.

Brain size, head size, and intelligence quotient in monozygotic twins

Many studies of monozygotic (MZ) twins have revealed evidence of genetic influences on intellectual functions and their derangement in certain neurologic and psychiatric diseases afflicting the forebrain. Relatively little is known about genetic influences on the size and shape of the human forebrain and its gross morphologic subdivisions. Using MRI and quantitative image analysis techniques, we examined neuroanatomic similarities in MZ twins and their relationship to head size and intelligence quotient (IQ). ANOVA were carried out using each measure as the dependent variable and genotype, birth order, and sex, separately, as between-subject factors. Pairwise correlations between measures were also computed. We found significant effects of genotype but not birth order for the following neuroanatomic measures: forebrain volume (raw, p < or = 0.0001; normalized by body weight, p = 0.0003); cortical surface area (raw, p = 0.002; normalized, p = 0.001); and callosal area (raw, p < or = 0.0001; normalized by forebrain volume, p = 0.02). We also found significant effects of genotype but not birth order for head circumference (raw, p = 0.0002; normalized, p < or = 0.0001) and full-scale IQ (p = 0.001). There were no significant sex effects except for raw head circumference (p = 0.03). Significant correlations were observed among forebrain volume, cortical surface area, and callosal area and between each brain measure and head circumference. There was no significant correlation between IQ and any brain measure or head circumference. These results indicate that: 1) forebrain volume, cortical surface area, and callosal area are similar in MZ twins; and 2) these brain measures are tightly correlated with one another and with head circumference but not with IQ in young, healthy adults.

Trends in pediatric asthma hospitalization rates: regional and socioeconomic differences

OBJECTIVE

Asthma hospitalization rates continue to increase nationally for children despite efforts by the National Institutes of Health and specialty organizations to improve outcomes through the dissemination of practice guidelines. To understand the generalizability of national trends to regional populations, we studied childhood hospitalizations over a 10-year period in four northeastern states.

DESIGN

Longitudinal analysis of hospitalization rates by patient residence and patient characteristics using state hospital discharge datasets.

POPULATION

Age < 18 years residing in Maine, New Hampshire, Vermont, or New York state during the period 1985 to 1994.

RESULTS

In multivariate analyses (controlling for age, sex, race/ethnicity, median household income, metropolitan status), we found that New York asthma hospitalization rates increased 3.8% per annum (95% confidence interval: 3.3, 4.2), whereas in New Hampshire, rates decreased 5.8% (95% confidence interval: 7.6, 4.1). Maine and Vermont rates did not change significantly during the study period. Increased asthma hospitalization rates were noted in black and Hispanic populations, in children residing in zip codes with lower median household incomes, and in those living in metropolitan areas. Hospitalization rates for nonasthma causes fell substantially. As a result, the proportion of hospital days attributed to childhood asthma increased in all population groups.

CONCLUSIONS

Asthma discharge rates measured by the state of residence or socioeconomic characteristic do not necessarily parallel national trends. None of the current hypotheses offered to explain national trends in asthma hospitalization rates (changes in disease severity, diagnostic substitution, or differences in the supply and character of medical care) can be the sole explanation of these regional trends. Efforts intended to improve asthma outcomes may benefit a greater number of children by redirecting resources toward specific populations identified through state hospital discharge datasets.

A comparison of clomiphene citrate and human menopausal gonadotropin for use in conjunction with intrauterine insemination

OBJECTIVE

To compare the outcome of superovulation using clomiphene citrate (CC) versus hMG in conjunction with IUI.

DESIGN

Sequentially assigned, observational study. Couples initially were assigned to receive either CC or hMG for three cycles.

SETTING

The Clinical Outpatient Department of the Dartmouth-Hitchcock Medical Center.

PATIENT(S)

Eighty-three infertile couples.

INTERVENTION(S)

IUI with hMG use.

MAIN OUTCOME MEASURE(S)

Conception rate, term pregnancy rate (PR), and pregnancy complications, such as spontaneous miscarriage and multiple gestation.

RESULT(S)

Of 83 couples who underwent at least one treatment cycle, 29 (35%) conceived during the study period. The relative rate of conception for hMG versus CC was 2.08 (95% confidence interval [CI], 0.93 to 4.68). The relative term PR was 2.10 (95% CI, 0.77 to 5.73) for hMG versus CC. There was no difference in the miscarriage rate for hMG versus CC.

CONCLUSION(S)

Both the conception rate and the term PR were higher using hMG, compared with CC, in combination with IUI, and showed a trend toward statistical significance.

The distance to community medical care and the likelihood of hospitalization: is closer always better?

OBJECTIVES

This study examined the influence that distance from residence to the nearest hospital had on the likelihood of hospitalization and mortality.

METHODS

Hospitalizations were studied for Maine. New Hampshire, and Vermont during 1989 (adults) and for 1985 through 1989 (children) and for mortality (1989) in Medicare enrollees.

RESULTS

After other known predictors of hospitalization (age, sex, bed supply, median household income, rural residence, academic medical center, and presence of nursing home patients) were controlled for, the adjusted rate ratio of medical hospitalization for residents living more than 30 minutes away was 0.85 (95% confidence interval [CI] = 0.82, 0.88) for adults and 0.78 (95% CI = 0.74, 0.81) for children, compared with those living in a zip code with a hospital. Similar effects were seen for the four most common diagnosis-related groups for both adults and children. The likelihood of hospitalization for conditions usually requiring hospitalization and for mortality in the elderly did not differ by distance.

CONCLUSIONS

Distance to the hospital exerts an important influence on hospitalization rates that is unlikely to be explained by illness rates.

Two-stage method of estimation for general linear growth curve models

We extend the linear random-effects growth curve model (REGCM) (Laird and Ware, 1982, Biometrics 38, 963-974) to study the effects of population covariates on one or more characteristics of the growth curve when the characteristics are expressed as linear combinations of the growth curve parameters. This definition includes the actual growth curve parameters (the usual model) or any subset of these parameters. Such an analysis would be cumbersome using standard growth curve methods because it would require reparameterization of the original growth curve. We implement a two-stage method of estimation based on the two-stage growth curve model used to describe the response. The resulting generalized least squares (GLS) estimator for the population parameters is consistent, asymptotically efficient, and multivariate normal when the number of individuals is large. It is also robust to model misspecification in terms of bias and efficiency of the parameter estimates compared to maximum likelihood with the usual REGCM. We apply the method to a study of factors affecting the growth rate of salmonellae in a cubic growth model, a characteristic that cannot be analyzed easily using standard techniques.

Effects of anesthetic technique on myocardial wall motion abnormalities during abdominal aortic surgery

OBJECTIVE

To assess the impact of regional supplemented general anesthesia (RSGEN) on regional myocardial function during abdominal aortic surgery (AAS).

DESIGN

Prospective randomized study.

SETTING

Single academic medical center.

PARTICIPANTS

Seventy-three patients scheduled for infrarenal aortic aneursymectomy.

INTERVENTIONS

Patients received standardized intraoperative anesthetic management consisting of either general anesthesia (GA; n = 37) or general anesthesia supplemented by epidural anesthesia (RSGEN; n = 36).

MEASUREMENTS AND MAIN RESULTS

Hemodynamic measurements and transesophageal echocardiograms (TEE) were obtained at eight intraoperative times. The electrocardiogram (ECG) was continuously recorded using Holter monitoring. Of the 56 patients with interpretable TEE recordings, 8 of 30 (27%) GA patients and 7 of 26 (27%) RSGEN patients developed new segmental wall motion abnormalities (SWMAs). There was no treatment effect on either the incidence (p = 0.23) or the intensity (p = 0.34) of SWMAs. Cross-clamping of the aorta was associated with the onset of new SWMAs (odds ratio, 8.2; 95% CI, 1.1 to 64; p = 0.04). Among the 63 patients with interpretable Holter recordings, 9 of 34 (26%) GA patients and 9 of 29 (31%) RSGEN patients exhibited intraoperative ischemia. There was no treatment effect on the incidence (p = 0.22) or intensity (p = 0.67) of ECG ischemia.

CONCLUSION

Despite providing modest hemodynamic depression, RSGEN did not reduce the incidence or intensity of either regional myocardial dysfunction or ECG ischemia. New SWMAs were temporally associated with cross-clamping of the aorta and tended to resolve with unclamping.

Superficial femoral artery stenoses: characteristics of progressing lesions

PURPOSE

The purpose of this study was to assess the effect of superficial femoral artery (SFA) stenosis morphologic characteristics and lesion location on the rate of atherosclerotic disease progression.

METHODS

We identified 19 patients who required arteriography for treatment of critical leg ischemia and who had previously undergone arteriography of that leg when minimal or no symptoms were present. These initial incidental arteriographic evaluations were performed during evaluation of arterial disease in another vascular bed from 4 to 81 months (mean, 32 months) previously. Distinct SFA stenoses or occlusion on the final arteriogram (n = 98) were characterized by their location, length, stenosis severity, and morphologic appearance on the initial arteriogram. The contribution of patient-specific risk factors to disease progression was also assessed.

RESULTS

Stenosis progression occurred independently among multiple lesions within the same patient (negligible intraclass correlation coefficient, r = 0.06). Lesions in the adductor canal region were more likely to occlude than lesions elsewhere in the SFA (adjusted odds ratio = 10.7; p = 0.03). Severity of initial lesion stenosis also was predictive of occlusion (adjusted odds ratio = 1.8; p = 0.04). However, most progressing lesions (93%) actually arose in areas of initially mild disease (stenoses < 50%) despite more severe initial lesions elsewhere. Increasing age (p = 0.023) and previous contralateral leg bypass (p = 0.036) were also associated with increasing rates of lesion progression. Smooth-asymmetric lesions progressed 11% more slowly than other lesion types (p = 0.003).

CONCLUSIONS

Our analysis of atherosclerotic SFA lesion progression in patients with critical ischemia shows that initial stenosis severity was associated with higher occlusion rates and that smooth-asymmetric lesions progressed more slowly than lesions with other morphologic characteristics. Severe stenoses usually arose from minimally diseased regions and progressed more rapidly than preexisting, more highly stenotic lesions. Most SFA occlusions resulted from disease progression in the adductor canal region whether or not antecedent lesions were seen on arteriography and whether or not more severe stenoses were initially present elsewhere. Increased age and history of previous contralateral bypass were patient-specific predictors of lesion progression.

Risk of squamous cell carcinoma of the skin in relation to plasma selenium, alpha-tocopherol, beta-carotene, and retinol: a nested case-control study

We conducted a nested case-control study of squamous cell skin cancer (SCC) to determine whether risk was related to plasma concentrations of selenium, alpha-tocopherol, beta-carotene, and retinol. We derived the study sample from participants in our Skin Cancer Prevention Study, all of whom had at least one basal cell or squamous cell skin cancer before study entry. Those who developed a new squamous cell skin cancer during the 3-5-year follow-up period were selected as cases (n = 132). Controls (n = 264) were chosen at random, with matching by age, sex, and study center, from among those who did not develop SCC but were being followed actively at the time the SCC case was diagnosed. Prediagnostic plasma samples were analyzed for alpha-tocopherol, beta-carotene, and retinol using high-performance liquid chromatography. Selenium determinations were made using instrumental neutron activation analysis. Odds ratios were computed using conditional logistic regression for matched samples. We found no consistent pattern of SCC risk associated with any of the nutrients examined. The odds ratios (95% confidence intervals) for the highest versus the lowest quartiles of beta-carotene, retinol, alpha-tocopherol, and selenium were 0.73 (0.38-1.41), 1.43 (0.77-2.64), 0.89 (0.43-1.85), and 0.86 (0.47-1.58), respectively. Thus, our data add to the growing body of evidence that these nutrients, at the concentrations we evaluated, are not related strongly to SCC risk.

Risk of basal cell and squamous cell skin cancers after ionizing radiation therapy. For The Skin Cancer Prevention Study Group

BACKGROUND

Human evidence that ionizing radiation is carcinogenic first came from reports of nonmelanoma skin cancers (NMSCs) on the hands of workers using early radiation devices. An increased risk of NMSC has been observed among uranium miners, radiologists, and individuals treated with x rays in childhood for tinea capitis (ringworm of the scalp) or for thymic enlargement; NMSC is one of the cancers most strongly associated with the atomic bombing of Hiroshima and Nagasaki. Although exposure to ionizing radiation is a known cause of NMSC, it is not yet clear whether therapeutic radiation causes both major histologic types of NMSC, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Additionally, the potentially modifying effects, such as latency, age when treated, and type of treatment, are not well understood.

PURPOSE

We investigated the relative risks of BCC and SCC associated with previous radiation therapy and evaluated these risks in relation to age and time since initial treatment and the medical condition for which radiation therapy was given.

METHODS

The study group comprised individual diagnosed with at least one BCC or SCC from January 1980 through February 1986, who were recruited to participate in a skin cancer prevention trial designed to test whether oral beta-carotene supplementation would reduce the risk of new NMSCs. Patients were identified through the dermatology and pathology records of academic medical centers in Hanover, NH; Los Angeles, CA; San Francisco, CA; and Minneapolis, MN. Each participant completed a questionnaire detailing lifetime residence, pigmentary characteristics, occupational and recreational sun exposure, and history of radiation therapy. At enrollment, a study dermatologist assessed skin type (tendency to burn or tan) and extent of actinic skin damage. Participants were followed with an annual dermatologic examination for an average of 4 years. Of the 5232 potentially eligible individuals, 1805 were enrolled in the trial. We excluded 112 patients who reported previous radiation therapy for skin cancer only and three with missing information on whether they were ever treated with radiation therapy, leaving 1690 patients for the analysis. Approximately 4% of the patients died or discontinued participation for other reasons during each study year. We examined time to occurrence of first new histopathologically confirmed BCC and SCC during the follow-up period in relation to history of radiation therapy (for reasons other than NMSC) using a proportional hazards model. A multiple end points survival model was used to compare the rate ratios (RRs) for BCC and SCC. We also used a longitudinal method of analysis to compute the RR of total new BCC and SCC tumors per person per study year associated with radiation therapy. Using this method, we additionally assessed the potential modifying effects of age at treatment, latency, and type of therapy. All P values were derived from two-sided statistical tests of significance.

RESULTS

Among the participants we studied, 597 developed a new BCC (n = 1553 tumors) and 118 developed a new SCC (n = 179 tumors). The time to first new BCC, but not SCC, was associated with prior radiation therapy (RR = 1.7; 95% confidence interval [CI] = 1.4-2.0 and RR = 1.0; 95% CI = 0.6-1.7, respectively; P = .03 for the difference between the RRs). The RR of total BCC tumors was slightly higher (RR = 2.3; 95% CI = 1.7-3.1), but it was still unity for SCC (RR = 1.0; 95% CI = 0.5-1.9). BCC risk appeared to increase with younger age at exposure and time since initially treated, although these effects were only marginally statistically significant (P for trend = .06 and .07, respectively). Also, risk of BCC was more strongly related to treatment for acne (RR = 3.3; 95% CI = 2.1-5.2) than other conditions.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that exposure to therapeutic radiation is associated with BCC but not with SCC.

Iron deficiency in Massachusetts communities: Socioeconomic and demographic risk factors among children

OBJECTIVES

This study examined the association between community rates of iron deficiency in children and sociodemographic characteristics of Massachusetts communities.

METHODS

Between April 1990 and March 1991, 238 273 Mssachusetts children 6 through 59 months of age were screened; iron deficiency was defined as an erythrocyte protopophyrin concentration of 0.62 micromol/L or higher and a blood lead level of less than 1.2 micromol/L. Sociodemographic data were obtained from the 1990 US Census.

RESULTS

Five percent of communities had iron deficiency rates greater than 13.9 per 100 children screened. Iron deficiency rate was positively associated with proportion of Southeast Asians (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.08, 1.12), proportion of Hispanics (OR = 1.008, 95% CI = 1.002, 1.013), and high school incompletion (OR = 1.028, 95% CI = 1.020, 1.035). Similarly, an examination of three Massachusetts cities indicated that the iron deficiency rate was higher for children with Southeast Asian (relative risk [RR] = 3.6, 95% CI = 3.3, 3.8) and Hispanic (RR = 1.6, 95% CI = 1.5, 1.8) surnames than for all other children.

CONCLUSIONS

Wide variation exists in iron deficiency rates for children in Massachusetts communities. Community iron deficiency was associated with low socioeconomic status and high proportions of Southeast Asians and Hispanics.

Mortality associated with low plasma concentration of beta carotene and the effect of oral supplementation

OBJECTIVE

To examine the relationship between beta carotene plasma concentration and beta carotene supplementation and risk of death from major disease causes.

DESIGN

Cohort study of plasma concentrations; randomized, controlled clinical trial of supplementation.

SETTING

Medical school-affiliated dermatology practices.

PATIENTS

A total of 1188 men and 532 women with mean age of 63.2 years, who had enrolled in a randomized clinical trial of beta carotene supplementation to prevent nonmelanoma skin cancer.

INTERVENTION

Oral beta carotene, 50 mg per day for a median of 4.3 years.

MAIN OUTCOME MEASURES

All-cause mortality and mortality from cardiovascular disease and cancer.

RESULTS

During a median follow-up period of 8.2 years, there were 285 deaths. Persons whose initial plasma beta carotene concentrations were in the highest quartile (>0.52 micromol/L [27.7 microg/dL]) had a lower risk of death from all causes (adjusted relative rate [RR], 0.52; 95% confidence interval [CI] 0.44 to 0.87) and from cardiovascular diseases (adjusted RR, 0.57; 95% CI, 0.34 to 0.95) compared with persons with initial concentrations in the lowest quartile (<0.21 micromol/L [11.2 microg/dL]). Patients randomly assigned to beta carotene supplementation showed no reduction in relative mortality rates from all causes (adjusted RR, 1.03; 95% CI, 0.82 to 1.30) or from cardiovascular disease (adjusted RR, 1.16; 95% CI, 0.82 to 1.64). There was no evidence of lower mortality following supplementation among patients with initial beta carotene concentrations below the median for the study group.

CONCLUSIONS

These analyses provide no support for a strong effect of supplemental beta carotene in reducing mortality from cardiovascular disease or other causes. Although the possibility exists that beta carotene supplementation produces benefits that are too small or too delayed to have been detected in this study, noncausal explanations should be sought for the association between plasma concentrations of beta carotene and diminished risk of death.

Utility of a risk assessment questionnaire in identifying children with lead exposure

OBJECTIVE

To evaluate the utility of the Centers for Disease Control and Prevention (CDC) Risk Questionnaire and a behavioral risk factor questionnaire in identifying children with blood lead concentrations of 0.48 mumol/L (10 micrograms/dL) or more.

DESIGN

Cross-sectional study of 463 urban Massachusetts children (6 to 72 months of age) screened for lead with venous blood.

RESULTS

Twenty-two percent of the children had elevated blood lead concentrations. Of the five CDC questions, only one was significantly associated with an increased adjusted odds ratio for elevated blood lead: having a sibling, housemate, or playmate who was followed up or treated for lead poisoning (odds ratio, 2.7; 95% confidence interval, 1.7 to 4.2; P < .001). Children who had at least one positive or equivocal response to any of the five CDC questions (n = 318 [68.7%]) were not at higher risk than were children who displayed a negative response to all five questions (odds ratio, 1.1; 95% confidence interval, 0.7 to 1.8; P = .69). Of nine behaviors surveyed, two were associated with an increased adjusted odds for elevated blood lead: use of a pacifier (odds ratio, 2.4; 95% confidence interval, 1.3 to 4.4; P = .01) and playing near the outside of the home (odds ratio, 3.4; 95% confidence interval, 2.0 to 5.8; P < .001).

CONCLUSIONS

In this population of children, the CDC risk questionnaire did not identify a group at higher risk for lead exposure. We suggest that practitioners in urban communities screen all children according to the same schedule. We conclude that risk factors differ by community and no risk questionnaire developed at the national level should be applied across communities to target screening.

Effects of intraoperative irradiation and intraoperative hyperthermia on canine sciatic nerve: neurologic and electrophysiologic study

PURPOSE

Late radiation injury to peripheral nerve may be the limiting factor in the clinical application of intraoperative radiation therapy (IORT). The combination of IORT with intraoperative hyperthermia (IOHT) raises specific concerns regarding the effects on certain normal tissues such as peripheral nerve, which might be included in the treatment field. The objective of this study was to compare the effect of IORT alone to the effect of IORT combined with IOHT on peripheral nerve in normal beagle dogs.

METHODS AND MATERIALS

Young adult beagle dogs were randomized into five groups of three to five dogs each to receive IORT doses of 16, 20, 24, 28, or 32 Gy to 5 cm of surgically exposed right sciatic nerve using 6 MeV electrons and six groups of four to five dogs each received IORT doses of 0, 12,16, 20, 24, or 28 Gy simultaneously with 44 degrees C of IOHT for 60 min. IOHT was performed using a water circulating hyperthermia device with a multichannel thermometry system on the surgically exposed sciatic nerve. Neurologic and electrophysiologic examinations were done before and monthly after treatment for 24 months. Electrophysiologic studies included electromyographic (EMG) examinations of motor function, as well as motor nerve conduction velocities studies.

RESULTS

Two years after treatment, the effective dose for 50% complication (ED50) for limb paresis in dogs exposed to IORT only was 22 Gy. The ED50 for paresis in dogs exposed to IORT combined with IOHT was 15 Gy. The thermal enhancement ratio (TER) was 1.5. Electrophysiologic studies showed more prominent changes such as EMG abnormalities, decrease in conduction velocity and amplitude of the action potential, and complete conduction block in dogs that received the combination of IORT and IOHT. The latency to development of peripheral neuropathies was shorter for dogs exposed to the combined treatment.

CONCLUSION

The probability of developing peripheral neuropathies in a large animal model was higher for IORT combined with IOHT, than for IORT alone. The dose required to produce the same level of late radiation injury to the sciatic nerve was reduced by a factor of 1.5 (TER) if IORT was combined with 44 degrees C of IOHT for 60 min.

Long-term morbidity following jejunoileal bypass. The continuing potential need for surgical reversal

OBJECTIVE

To review the late sequelae of jejunoileal bypass (JIB) and the potential role of late surgical reversal in ameliorating morbidity and mortality following JIB.

DESIGN

Patients who underwent JIB between 1965 and 1977 were contacted and pertinent health-event information was gathered. Early sequelae were defined as disorders occurring within the first 2 years after JIB; late sequelae were those occurring after 2 years. Health events occurring between 0 and 23 years after JIB were documented.

SETTING

A private, tertiary referral center.

PATIENTS

Patients underwent JIB for morbid obesity that had failed medical and/or psychiatric interventions.

MAIN OUTCOME MEASURES

Body mass index (BMI) (weight kilograms divided by the square of the height in meters), diarrhea, electrolyte imbalance, acute, and chronic liver disease, renal disease, JIB reversal, reason for JIB reversal, death, and cause of death.

RESULTS

A total of 453 morbidity obese patients underwent JIB. By 2 years following JIB, the mean (+/- SD) BMI dropped from 49.3 +/- 8.1 to 31.1 +/- 0.8 and remained at this level until year 15, after which weight gradually increased (BMI, 35.4 +/- 3.1). The most severe early complication was acute liver failure, which occurred in 7% of patients and caused seven deaths. At 15 years, the actuarial probability of the most common serious late complications related to JIB were renal disease (37%), with two deaths; diarrhea (29%); and liver disease (10%), with three deaths. One hundred thirty-eight patients (31%) had a bypass reversal. The most common indications for reversal were diarrhea and electrolyte disturbance (29%), renal disease (19%), and liver disease (17%). Fifty-six patients died more than 30 days after JIB: 64% before JIB reversal, 13% at the time of reversal, and 23% subsequently.

CONCLUSIONS

Jejunoileal bypass is associated with progressive accrual of serious, sometimes life-threatening complications. Lifelong follow-up for early diagnosis and surgical reversal before life is threatened should reduce the morbidity and mortality associated with this procedure.