Early Midterm Results After Valve Replacement With Contemporary Pericardial Prostheses for Severe Aortic Stenosis.

BACKGROUND: Clinical studies have demonstrated improved gradients after aortic valve replacement with the Trifecta (TR) valve (Abbott Cardiovascular, St Paul, MN) as compared with the Carpentier-Edwards Magna Ease (ME) valve (Edwards Lifesciences, Irvine, CA). Clinical benefits of this strategy have not been demonstrated. METHODS: Patients undergoing aortic valve replacement for severe aortic stenosis with either valve were included. Patients were excluded if they underwent concomitant procedures other than coronary artery bypass grafting. Inverse proportion treatment weighting was used in the analysis. The primary outcome was a composite of cardiac mortality, need for reintervention, and freedom from first congestive heart failure (CHF). Secondary outcomes were all-cause mortality, the composite components, and cumulative CHF admission. Follow-up echocardiograms were assessed in a cohort of patients to assess structural valve degeneration. RESULTS: There were 331 patients in the TR group and 360 patients in the ME group. The TR group had more women (48% vs 32%, P < .001) with smaller roots (left ventricular outflow tract diameter: TR, 2.11 cm; ME, 2.17 cm; P < .001). After weighting there was no significant difference in the composite measure between groups (P > .05). There was no difference in all-cause mortality (hazard ratio, 0.82; 95% confidence interval, 0.42-1.59; P = .56), and 5-year survival was 91.9% in the ME group and 93.4% in the TR group. There was no difference in cardiac death, reintervention, or first onset of CHF or incidence of structural valve degeneration between groups. There was no difference in the rate of admissions for CHF per 100 patients between the 2 valve types (P = .19). CONCLUSIONS: Early hemodynamic benefits have not translated into differences in medium-term clinical outcomes between these 2 valves. Long-term follow-up is necessary.

Using balance statistics to determine the optimal number of controls in matching studies.

When a randomized controlled trial is not feasible, investigators typically turn to matching techniques as an alternative approach to evaluate the effectiveness of health care interventions. Matching studies are designed to minimize imbalances on measured pre-intervention characteristics, thereby reducing bias in estimates of treatment effects. Generally, a matching ratio up to 4:1 (control to treatment) elicits the lowest bias. However, when matching techniques are used in prospective studies, investigators try to maximize the number of controls matched to each treated individual to increase the likelihood that a sufficient sample size will remain after attrition. In this paper, we describe a systematic approach to managing the trade-off between minimizing bias and maximizing matched sample size. Our approach includes the following three steps: (1) run the desired matching algorithm, starting with 1:1 (one control to one treated individual) matching and iterating until the maximum desired number of potential controls per treated subject is reached; (2) for each iteration, test for covariate balance; and (3) generate numeric summaries and graphical plots of the balance statistics across all iterations in order to determine the optimal solution. We demonstrate the implementation of this approach with data from a medical home pilot programme and with a simulation study of populations of 100,000 in which 1000 individuals receive the intervention. We advocate undertaking this methodical approach in matching studies to ensure that the optimal matching solution is identified. Doing so will raise the overall quality of the literature and increase the likelihood of identifying effective interventions.

Estimating measurement error when annualizing health care costs.

OBJECTIVE: Health insurers routinely annualize members' health care costs for reporting, predicting high cost cases and evaluating health management programmes. Annualization is the practice of extrapolating to a yearly cost from less than a year of data. In this paper, we systematically estimate the measurement error inherent in this approach. STUDY DESIGN: The paper uses a retrospective observational study using longitudinal claims data from three types of insured populations: Medicare managed care, public employees and a self-insured employer. METHODS: The unit of analysis was a block 'year' consisting of 12 consecutive months of cost data for any individual member. These blocks were constructed recursively allowing use of all available data that an individual could contribute. We tested the accuracy of the annualized costs by calculating the absolute error (AE) representing the difference, in dollars, between the actual annual costs and the predicted annual costs, and the absolute percentage error (APE) which is the absolute error divided by the actual 12-month costs. RESULTS: Under the best case scenario (when 11 months of data were used to annualize costs), the mean AE ranged from approximately $2700 for the Medicare population to about $400 for the two working-aged populations; and the mean APE ranged from 9.6% to 11.0% in the three populations. Accuracy diminished systematically with fewer months of available data. CONCLUSIONS: Due to the largely unpredictable nature of monthly costs, annualization can produce substantial measurement error. Given the importance of cost metrics for decision making, we offer several alternative approaches that insurers should consider to improve measurement accuracy.

Awareness of necessity to call 9-1-1 for stroke symptoms, upstate New York.

INTRODUCTION: Stroke is the third leading cause of death and a leading cause of disability in New York State. A New York study determined that only 19.9% of patients arrived at a designated stroke center within 3 hours of symptom onset. Yet, receiving treatment within 90 minutes of stroke symptom onset is optimal for improved outcomes. Delay in recognition of stroke symptoms and their severity contributes to treatment delay. METHODS: A random-digit-dialed, list-assisted telephone survey about stroke knowledge was administered to 1789 adults aged 30 years or older in upstate New York in 2006. Bivariate and regression analysis were used to examine factors associated with intent to call 9-1-1 for symptoms of stroke. RESULTS: The largest proportion of respondents (72.4%; 95% confidence interval [CI], 69.9%-74.8%) reported they would call 9-1-1 if they noticed they or someone else had difficulty speaking, and the fewest (33.3%; 95% CI, 30.7%-36.0%) respondents reported they would call 9-1-1 for trouble seeing or double vision. Multivariate analysis found that those who had a history of delay in getting medical care in the past 6 months had decreased odds of intending to call 9-1-1 for stroke symptoms (difficulty speaking: adjusted odds ratio [AOR], 0.76; 95% CI, 0.58-1.00; trouble seeing: AOR, 0.69; 95% CI, 0.53-0.91; facial droop: AOR, 0.85; 95% CI, 0.65-1.11; arm weakness: AOR, 0.80; 95% CI, 0.63-1.03). Age, education, and history of a stroke or heart event were not consistently associated with intent to call 9-1-1. CONCLUSION: Survey respondents do not interpret some stroke symptoms as urgent enough to activate the emergency medical system. History of delaying care is a behavioral pattern that influenced intent to call 9-1-1.

Regression analysis of a disease onset distribution using diagnosis data.

We consider methods for estimating the effect of a covariate on a disease onset distribution when the observed data structure consists of right-censored data on diagnosis times and current status data on onset times amongst individuals who have not yet been diagnosed. Dunson and Baird (2001, Biometrics 57, 306-403) approached this problem using maximum likelihood, under the assumption that the ratio of the diagnosis and onset distributions is monotonic nondecreasing. As an alternative, we propose a two-step estimator, an extension of the approach of van der Laan, Jewell, and Petersen (1997, Biometrika 84, 539-554) in the single sample setting, which is computationally much simpler and requires no assumptions on this ratio. A simulation study is performed comparing estimates obtained from these two approaches, as well as that from a standard current status analysis that ignores diagnosis data. Results indicate that the Dunson and Baird estimator outperforms the two-step estimator when the monotonicity assumption holds, but the reverse is true when the assumption fails. The simple current status estimator loses only a small amount of precision in comparison to the two-step procedure but requires monitoring time information for all individuals. In the data that motivated this work, a study of uterine fibroids and chemical exposure to dioxin, the monotonicity assumption is seen to fail. Here, the two-step and current status estimators both show no significant association between the level of dioxin exposure and the hazard for onset of uterine fibroids; the two-step estimator of the relative hazard associated with increasing levels of exposure has the least estimated variance amongst the three estimators considered.

California surveillance for pesticide-related illness and injury: coverage, bias, and limitations.

The California Pesticide Illness Surveillance Program (PISP) is a major resource for pesticide illness epidemiology. This work attempts to improve characterization of pesticide illness in California, evaluate case ascertainment of the PISP and identify PISP's limitations and biases for studying the incidence and epidemiology of pesticide-related illness. Abstractors collected standardized information from 1994-1996 PISP files, poison control logs, hospital records, and death certificates. Linkage produced a merged file of all records that documented consideration of pesticide exposure as a cause of ill health. We identified 23 deaths and estimated 1,310 hospitalizations attributable to pesticide exposure, corresponding to 0.024 fatalities and 1.38 hospitalizations (95% confidence interval [CI] = 1.01-1.74) per 100,000 California population person-years. Most intoxications followed domestic exposures and were not reported to the surveillance program, which identified primarily occupational exposures. Excluding groups of five or more, we estimated 16% ascertainment (CI = 0.05-0.27) for non-agricultural occupational cases. Agricultural connections increased the probability of ascertainment to about 50%, cultural and economic barriers notwithstanding. Surveillance records existed for all identified episodes in which five or more people were exposed. California pesticide surveillance data appear complete for mass exposures, and adequate to characterize agricultural and occupational exposures. Work is needed to explore domestic exposures and occurrences beyond the reach of the health care system.

Understanding the increased risk of neural tube defect-affected pregnancies among Mexico-born women in California: immigration and anthropometric factors.

Mexico-born women in the United States have an unexplained twofold increased risk of neural tube defect (NTD)-affected pregnancies. We examined whether immigration characteristics were associated with the NTD risk and whether anthropometric factors contributed to the increased risk among Mexico-born women. Data were derived from a large population-based case-control study in California. In-person interviews were conducted with mothers of 538 (88% of eligible) NTD-affected fetuses/infants and mothers of 539 (88%) randomly selected non-malformed control infants. The crude odds ratio (OR) for NTDs among all Mexico-born women, women residing <2 years in the US, and women >16 years old at immigration compared with non-Hispanic white women was 2.4 [95% confidence interval (CI) = 1.8, 3.3], 7.2 [95% CI = 3.7, 14.0] and 3.0 [95% CI = 2.0, 4.4], respectively. Risk for second- or third-generation Mexican-Americans was similar to that of white women. The crude OR for all Mexico-born women was reduced from 2.4 to 2.0 [95% CI = 1.3, 3.0] and for those residing <2 years in the US from 8.4 to 7.1 [95% CI = 3.2, 15.3] after adjustment for maternal body mass index (BMI), height, compromised diet, diabetes, and other known risk factors. In term pregnancies, additional adjustment for pregnancy weight gain reduced the OR in all Mexico-born women and recent immigrants by 16% and 25%, respectively. Low pregnancy weight gain (<10 vs. 10-14 kg) was particularly associated with increased NTD risk among Mexico-born women (OR(ADJ) = 5.8; 95% CI = 2.1, 15.8). Findings indicate that recent Mexican immigrants have a sevenfold increased risk for NTDs. Maternal BMI and height contributed very little, and inadequate weight gain contributed modestly to the NTD risk disparity for Mexican immigrants.

Agricultural dust exposure and respiratory symptoms among California farm operators.

OBJECTIVE: To study whether dust exposure in California agriculture is a risk factor for respiratory symptoms. METHODS: A population-based survey of 1947 California farmers collected respiratory symptoms, occupational and personal exposures. Associations between dust and respiratory symptoms were assessed by logistic regression models. RESULTS: The prevalence of persistent wheeze was 8.6%, chronic bronchitis 3.8%, chronic cough 4.2%, and asthma 7.8%. Persistent wheeze was independently associated with dust in a dose-response fashion odds ratio, 1.2 (95% confidence interval[CI]=0.8-2.0) and 1.8 (95% CI=1.1-3.2) for low and high time in dust. A borderline significant association between chronic bronchitis and dust exposure was found. Asthma was associated with keeping livestock, but not with dust exposure. CONCLUSIONS: Occupational dust exposure among California farmers, only one third of whom tended animals, was independently associated with chronic respiratory symptoms.

The relation of occupational organic solvent exposure to symptom reporting in a sample of white and Chinese midlife women.

OBJECTIVE: This study examined the relation of occupational solvent exposure to menopausal and other symptoms in midlife women. METHODS: We conducted a cross-sectional study of 480 Chinese and 494 white women, aged 40-55 years, in Northern California. Levels of exposure to organic solvents (none, low, medium, or high) were assigned to each current job using a job-exposure matrix. RESULTS: A lower proportion of women with low occupational organic solvent exposure reported hot flashes or night sweats than working women with no solvent exposure (adjusted prevalence odds ratio [APOR] = 0.48, 95% confidence interval [CI] = 0.19-1.21). A greater proportion of women with high solvent exposure reported forgetfulness than women with no exposure (APOR = 2.51, 95% CI = 1.12-5.63). CONCLUSIONS: Some symptom reporting in midlife women was related to their occupational organic solvent exposure.

Self-reported dermatitis and skin cancer in California farm operators.

BACKGROUND: High rates of skin diseases and higher non-melanoma skin cancer rates have been reported in farmers. METHODS: Self-report of dermatitis and skin cancer was among the information collected from 1947 California farm operators, mostly men, in a telephone survey. The majority of the farmers cultivated fruits, nuts, or other field crops. RESULTS: Dermatitis was reported by 8.9% of men and 15.8% of women during the previous 12 months. In a logistic regression model, female gender (OR 2.0, 95% confidence interval 1.3-3.0) and respiratory atopy (OR 1.4, 1.01-1.90) were the only significant independent risk factors for reported dermatosis. There was significantly less reporting of skin cancer among field farmers when compared to others. Regular sunscreen use was reported significantly more often by women (42%) as compared to men (11%). CONCLUSIONS: More in-depth studies are needed to get information on the role of agrochemicals as risk factors for dermatitis and skin cancer.

Tracking career satisfaction and perceptions of quality among US obstetricians and gynecologists.

OBJECTIVE: To assess recent trends in professional satisfaction, perceptions of ability to provide high-quality care, and perceptions of ability to obtain needed services for patients in a national sample of obstetricians and gynecologists; to compare obstetrician-gynecologists with physicians in other specialties; and to identify demographic, professional, and practice characteristics associated with high career satisfaction. METHODS: We used data from the 1996-1997 (n=12,385; response rate, 65%) and 1998-1999 (n=12,280; response rate, 61%) waves of the nationally representative Community Tracking Study physicians' survey. The principal outcome measures were one item related to overall career satisfaction, six items measuring physicians' perceptions of their ability to provide high-quality care, and five items measuring physicians' perceptions of their ability to obtain needed services for patients. All results were weighted and adjusted to reflect the complex survey design. RESULTS: In 1996-1997, 34% of obstetrician-gynecologists (n=545) were very satisfied with their careers, and 24% were very or somewhat dissatisfied. Up to 45% perceived significant barriers to the delivery of high-quality care, and up to 58% were unable to "almost or almost always" obtain necessary services for patients. Results in 1998-1999 (n=484 obstetricians and gynecologists) were similar, except for a deterioration in perceived amount of time with patients and ability to obtain high-quality ancillary services. In comparison with primary care physicians, obstetrician-gynecologists were less satisfied (P=.001); in comparison with both primary care physicians and general surgeons, they had more problems delivering high-quality care (P<.001) and greater difficulties obtaining needed services for patients (P<.001). Controlling for selected demographic and professional characteristics, higher career satisfaction was associated with age greater than 65 years, practicing in small metropolitan areas and in academic settings, and having better perceptions of quality and ability to obtain services (P<.05). CONCLUSION: Although most obstetricians and gynecologists are satisfied with their careers, many are experiencing significant professional distress.

Agricultural injury in California migrant Hispanic farm workers.

BACKGROUND: Agriculture is among the most hazardous industries in the United States. METHODS: A longitudinal study of injury among migrant Hispanic farm workers residing in six Northern California Migrant Family Housing Centers (MHCs) during the 1997 harvest season was conducted. Participants completed an initial interviewer-administered work-and-health questionnaire at the beginning of the harvest season addressing the preceding year; there were three periodic follow-up surveys. RESULTS: There were 1,201 adult farm workers (participation 85.2%) who completed the initial questionnaire. Of these, 837 (69.7%) completed the final follow-up survey. There were 86 agricultural injuries (incidence 9.3/100 full-time equivalent employees (FTEs), 95% CI 7.5-11.5/100 FTE). Increased risk for agricultural injury occurred among women paid piece-rate (RR 4.9, 95% CI 1.8-12.8). Sprains and strains were most common (31%), followed by lacerations (12%). CONCLUSIONS: Agricultural injury experience in this cohort is comparable to that of agricultural workers in other U.S. settings. Increased risk among women paid piece-rate suggests further study and potential policy changes regarding payment regimens. Heterogeneity of injury in this population presents a major prevention challenge. In view of high frequency of strain and sprain injuries, ergonomic interventions deserve further study.

Use of protective equipment among California farmers.

BACKGROUND: Agriculture is a hazardous industry associated with many occupational injuries and illnesses. We describe California farmers' self-reported exposure to five agricultural hazards and their use of protective equipment. METHODS: A telephone survey of 1,947 California farmers recorded information on occupational exposure, health outcomes and use of protective equipment to lessen risk from exposure to dust, sun, noise, pesticides and tractors. RESULTS: Over 93% of respondents reported using personal protection around pesticides; however, fewer than 1/3 used consistent protection against other hazards. Younger age and male sex were associated with better use of protection from dust, noise, pesticide and tractors, but negatively associated with sun protection. There was no consistent relationship of protective behaviors with cigarette smoking, living on the farm, marital status, or time in non-administrative farmwork. Risk perception was strongly associated with behavior; farmers concerned about specific health problems were much more likely to use protective equipment. CONCLUSIONS: Some farmer characteristics are associated with more safe behaviors, but efforts to encourage protective behaviors on farms should be broadly based in view of a lack of a single risk-taking profile among California farmers.

Physician career satisfaction across specialties.

BACKGROUND: The career satisfaction and dissatisfaction physicians experience likely influence the quality of medical care. OBJECTIVE: To compare career satisfaction across specialties among US physicians. METHODS: We analyzed data from the Community Tracking Study of 12 474 physicians (response rate, 65%) for the late 1990s. Data are cross-sectional. Two satisfaction variables were created: very satisfied and dissatisfied. Thirty-three specialty categories were analyzed. RESULTS: After adjusting for control variables, the following specialties are significantly more likely than family medicine to be very satisfying: geriatric internal medicine (odds ratio [OR], 2.04); neonatal-perinatal medicine (OR, 1.89); dermatology (OR, 1.48); and pediatrics (OR, 1.36). The following are significantly more likely than family medicine to be dissatisfying: otolaryngology (OR, 1.78); obstetrics-gynecology (OR, 1.61); ophthalmology (OR, 1.51); orthopedics (OR, 1.36); and internal medicine (OR, 1.22). Among the control variables, we also found nonlinear relations between age and satisfaction; high satisfaction among physicians in the west north Central and New England states and high dissatisfaction in the south Atlantic, west south Central, Mountain, and Pacific states; positive associations between income and satisfaction; and no differences between women and men. CONCLUSIONS: Career satisfaction and dissatisfaction vary across specialty as well as age, income, and region. These variations are likely to be of interest to residency directors, managed care administrators, students selecting a specialty, and physicians in the groups with high satisfaction and dissatisfaction.

Injury risks in children of California migrant Hispanic farm worker families.

BACKGROUND: Few data are available addressing occupational and other injury risks among children of migrant Hispanic farm workers. METHODS: We conducted the U.C. Davis Farm Worker Injury Study (UCD-FWIS), a longitudinal follow-up study of injury among migrant Hispanic farm worker families living in six Northern California Migrant Housing Centers (MHCs). Nine hundred forty-one children (age < 18 years) were interviewed through parental proxy. RESULTS: Fifty-one injuries resulting in medical care or at least one-half day of lost or restricted work or school time occurred among 49 children (3.8 injuries/100 person-years). Open wounds (31.4%) and fractures (29.4%) were most common. Falls comprised over one-third of the cases, followed by being struck and bicycle injuries. Over three-quarters of subjects never use a helmet when riding a bicycle. Seventy-eight (8.3%) children reported employment in the preceding year, typically involving manual agricultural tasks. Two injury cases were occupational and involved agricultural work. CONCLUSIONS: Occupational injury was uncommon in this group of children in migrant Hispanic farm worker families. Injury prevention in this population should include a focus on the home and surrounding environment as well as the work place.