Biomedical subjects

P Heagerty

Publications and source records attributed to P Heagerty.

10 recordsLinked to original sources

PubMed2005

An evaluation of state firearm regulations and homicide and suicide death rates.

OBJECTIVE: To determine if any of five different state gun laws were associated with firearm mortality: (1) "shall issue" laws permitting an individual to carry a concealed weapon unless restricted by another statute; (2) a minimum age of 21 years for handgun purchase; (3) a minimum age of 21 years for private handgun possession; (4) one gun a month laws which restrict handgun purchase frequency; and (5) junk gun laws which ban the sale of certain cheaply constructed handguns. DESIGN: A cross sectional time series study of firearm mortality from 1979 to 1998. SETTING: All 50 states and the District of Columbia. SUBJECTS: All residents of the United States. MAIN OUTCOME MEASURES: Firearm homicides, all homicides, firearm suicides, and all suicides. RESULTS: When a "shall issue" law was present, the rate of firearm homicides was greater, RR 1.11 (95% confidence interval 0.99 to 1.24), than when the law was not present, as was the rate of all homicides, RR 1.08 (95% CI 0.98 to 1.17), although this was not statistically significant. No law was associated with a statistically significant decrease in the rates of firearm homicides or total homicides. No law was associated with a statistically significant change in firearm suicide rates. CONCLUSION: A "shall issue" law that eliminates most restrictions on carrying a concealed weapon may be associated with increased firearm homicide rates. No law was associated with a statistically significant reduction in firearm homicide or suicide rates.

Adolescent↗

PubMed2001

The Longitudinal Assessment of Imaging and Disability of the Back (LAIDBack) Study: baseline data.

STUDY DESIGN: Prospective cohort study of randomly selected Veterans Affairs (VA) outpatients. OBJECTIVE: To determine the prevalence of magnetic resonance imaging (MRI) findings in the lumbar spine among persons without current low back pain or sciatica and to examine which findings are related to age or previous back symptoms. SUMMARY OF BACKGROUND INFORMATION: Previous studies of patients without low back pain have not explored the possible association of various MRI findings to past symptoms. METHODS: We randomly selected an age-stratified sample of subjects without low back pain in the past 4 months from clinics at a VA hospital. We collected information on demographics, comorbidity, functional status, and quality of life. MR images were obtained using a standardized protocol through each of the five lumbar disc levels. RESULTS: Of 148 subjects, 69 (46%) had never experienced low back pain. There were 123 subjects (83%) with moderate to severe desiccation of one or more discs, 95 (64%) with one or more bulging discs, and 83 (56%) with loss of disc height. Forty-eight subjects (32%) had at least one disc protrusion and 9 (6%) had one or more disc extrusions. CONCLUSION: Many MR imaging findings have a high prevalence in subjects without low back pain. These findings are therefore of limited diagnostic use. The less common findings of moderate or severe central stenosis, root compression, and extrusions are likely to be diagnostically and clinically relevant.

Adult↗

PubMed2001

Common bile duct injury during laparoscopic cholecystectomy and the use of intraoperative cholangiography: adverse outcome or preventable error?

BACKGROUND: Common bile duct (CBD) injury is a serious complication of laparoscopic cholecystectomy (LC). Predictors of this adverse outcome have not been well documented. HYPOTHESIS: Surgeon experience and the use of intraoperative cholangiography (IOC) are associated with a decreased rate of major CBD injury during LC. DESIGN: A retrospective population-based cohort study. SETTING: Washington State hospital discharge database reports from 1991 through 1998. PATIENTS: Discharge reports were searched for International Classification of Diseases, Ninth Revision, procedure codes consistent with LC and then evaluated for procedure codes for CBD repair and reconstruction within 90 days of LC. MAIN OUTCOME MEASURE: The rate of CBD injury in patients undergoing LC based on the surgeon's experience and IOC use. RESULTS: In all, 30 630 LCs and 76 major CBD injuries (2.5/1000 operations) were identified in this analysis. There were no significant differences between injured and noninjured patients in demographics, disease, payer status, or hospital variables. A CBD injury occurred in 3.2 of 1000 LCs in the early case order of surgeons compared with 1.7 per 1000 at later points (P = .01) (relative risk, 1.81; 95% confidence interval, 1.44-2.88). The rate of injury in LCs performed without IOC was 3.3 per 1000 compared with 2.0 per 1000 in LCs with IOC (P = .02) (relative risk, 1.7; 95% confidence interval, 1.1-2.6). Surgeon's experience and IOC use were independent predictors of injury. CONCLUSIONS: The rate of CBD injury is significantly lower when IOC is used. This effect is magnified during the early experience of surgeons. Systematic use of IOC may significantly reduce the rate of CBD injury.

Cholangiography↗

PubMed2001

Pharmacologic stress testing for coronary disease diagnosis: A meta-analysis.

BACKGROUND: Although noninvasive pharmacologic stress tests are widely used, their relative performance is not clear. We compared the performance of pharmacologic stress tests combined with echocardiography or nuclear imaging for the diagnosis of coronary disease. METHODS: We performed a regression meta-analysis of published data. We included studies published between January 1975 and June 1999 in which subjects underwent echocardiographic or single-photon emission computed tomography (SPECT) stress testing with adenosine, dipyridamole, or dobutamine for diagnosis of coronary artery disease. All subjects also underwent coronary angiography. Two independent reviewers abstracted population characteristics, technical factors, methodologic factors, and results and calculated test sensitivity and specificity. RESULTS: Eighty-two studies met the inclusion criteria. The sensitivity of dipyridamole SPECT imaging, 89% (95% CI, 84%-93%), was higher than that of dipyridamole echocardiography, but the specificity of dipyridamole SPECT imaging, 65% (95% CI, 54%-74%), was lower than that of dipyridamole echocardiography. Dipyridamole and adenosine tests had similar sensitivities and specificities. The sensitivity of dobutamine echocardiography, 80% (95% CI, 77%-83%) was similar to that of dobutamine SPECT imaging, but dobutamine echocardiography had a higher specificity, 84% (95% CI, 80%-86%) than dobutamine SPECT imaging did. CONCLUSIONS: The findings of our study can be used to guide the selection of the optimal pharmacologic stress test for each patient. Maximum sensitivity can be attained by use of a vasodilator combined with SPECT imaging. Maximum specificity can be attained by use of a vasodilator with echocardiography. The highest combination of sensitivity and specificity can be attained with dobutamine echocardiography.

Adenosine↗

PubMed2000

Readiness for HIV vaccine trials: changes in willingness and knowledge among high-risk populations in the HIV network for prevention trials. The HIVNET Vaccine Preparedness Study Protocol Team.

Longitudinal data were analyzed to determine changes in willingness to participate in HIV vaccine efficacy trials and knowledge of vaccine trial concepts among populations at high risk of HIV-1 infection. Gay men (MSM), male and female injection drug users, and non-injecting women at heterosexual risk were recruited (n = 4892). Follow-up visits occurred every 6 months up to 18 months. Willingness was significantly lower at follow-up visits compared with at baseline. Knowledge levels increased for all study populations. Problematic concepts were possible effects of the vaccine on the immune system and lack of knowledge about efficacy of a vaccine before the start of a trial. For concepts concerning safety, blinding, and guarantees of future participation in trials, MSM men had significant increases in knowledge, but little to no change occurred for the other populations. An increase in knowledge was associated with becoming not willing, particularly among MSM with low knowledge levels. At least half of high-risk participants were consistently willing to participate in future vaccine efficacy trials and with basic vaccine education, knowledge levels increased. Continued educational efforts at the community and individual level are needed to address certain vaccine trial concepts and to increase knowledge levels in all potential study populations.

AIDS Vaccines↗

PubMed1999

Correlates of condom failure in a sexually active cohort of men who have sex with men.

Condom failure (slippage or breakage) has been shown to be associated with HIV seroconversion among men who have sex with men (MSM), but predictors of failure have been poorly elucidated. Of 2592 HIV-seronegative MSM participants in the HIV Network for Prevention Trials (HIVNET) multisite Vaccine Preparedness Study who reported condom use for anal sex in the 6 months before enrollment, condom failure was reported by 16.6%, with failure rates of 2.1/100 episodes of condom usage (2.5 failures/100 episodes for receptive anal sex and 1.9/100 episodes for insertive anal sex). In separate multivariate models evaluating predictors of condom failure reported by the insertive and receptive partners, more frequent condom use was associated with a decreased per-condom failure rate and amphetamine and heavy alcohol use with increased rates in both models. Being employed, having private medical insurance, and using lubricants for >80% of anal sex acts were significantly associated with decreased failure rates in the insertive model. Safer sex counseling should particularly target men of lower socioeconomic status, promote proper and consistent use of condoms with appropriate lubricants, and address the impact of drug use, especially amphetamines and alcohol, on condom failure.

Adult↗

PubMed1999

Prediction using partly conditional time-varying coefficients regression models.

Data collected longitudinally in time provide the opportunity to develop predictive models of future observations given current data for an individual. Such models may be of particular value in defining individuals at high risk and thereby in suggesting subgroups for targeting of prevention intervention research efforts. In this paper, we propose a method for estimating predictive functions. The method uses an extension of the marginal regression analysis methods of Liang and Zeger (1986, Biometrika 73, 13-22) and is implemented using simple estimating equations. A key feature of the models is that regression coefficients are modelled as smooth functions of the times both at and for prediction. Data from a study of obesity in childhood and early adulthood is used to demonstrate the methodology. Criteria for defining individuals to be at high risk can be defined on the basis of estimated predictive functions. We suggest methods for evaluating the diagnostic accuracy (sensitivity and specificity) of such rules using cross-validation. The method holds promise as a robust and technically easy way of evaluating information about future prognosis that may be gleaned from a patient's current and past clinical status.

Adolescent↗

PubMed1998

Readiness of high-risk populations in the HIV Network for Prevention Trials to participate in HIV vaccine efficacy trials in the United States.

OBJECTIVE: To determine the willingness of populations at high risk of HIV-1 infection to participate in HIV vaccine efficacy trials, determine factors influencing decision-making, and evaluate knowledge levels of vaccine trial concepts. DESIGN: Cross-sectional study. METHODS: HIV-1-negative homosexual men, male and female injecting drug users and non-injecting women at heterosexual risk were recruited in eight cities in the United States (n=4892). RESULTS: A substantial proportion of the study population (77%) would definitely (27%) or probably (50%) be willing to participate in a randomized vaccine efficacy trial. Increased willingness was associated with high-risk behaviors, lower education level, being uninsured or covered by public insurance, and not having been in a previous vaccine preparedness study. Altruism and a desire for protection from the vaccine were major motivators for participation. Major concerns included positive HIV-1 antibody test due to vaccine, safety of the vaccine, and possible problems with insurance or foreign travel. Baseline knowledge of vaccine trial concepts was low. CONCLUSIONS: It is likely that high-risk volunteers will be willing to enroll in HIV vaccine efficacy trials. A variety of participant and community educational strategies are needed to address participant concerns, and to ensure understanding of key concepts prior to giving consent for participation.

AIDS Vaccines↗

PubMed1998

Rectal microbicides for U.S. gay men. Are clinical trials needed? Are they feasible? HIVNET Vaccine Preparedness Study Protocol Team.

BACKGROUND AND OBJECTIVES: Incomplete condom use during anal sex persists among gay men; microbicides may provide additional protection. Despite the absence of efficacy or safety data, many gay men use sexual lubricants containing nonoxynol-9 (N-9), a detergent-based spermicide under evaluation for efficacy as a vaginal microbicide. GOAL: Evaluate unprotected sex, lubricant use, and attitudes regarding possible participation in clinical trials of rectal microbicides among high-risk human immunodeficiency virus-(HIV) seronegative U.S. gay men in six cities. STUDY DESIGN: A total of 3,257 gay men were interviewed and responded to a self-administered questionnaire at enrollment into a longitudinal cohort study of HIV seroincidence. RESULTS: Among 2,216 men who practiced receptive anal intercourse in the previous 6 months, 438 (20%) reported they never used condoms. More than three fourths of 3,093 men who had anal sex used lubricants more than 80% of the time. 41% of whom actively sought N-9 containing products. About two thirds said they were definitely or probably willing to participate in rectal microbicide clinical trials. CONCLUSION: Condom use is imperfect among men who report anal sex. N-9 lubricants are popular. Most gay men in this cohort indicate willingness to participate in rectal microbicide studies.

Adolescent↗

PubMed1992

Quantitative PCR with internal controls.

We examine the use of internal controls for estimating the expected initial copy number of the target in a polymerase chain reaction (PCR). We base our investigation on an extended branching-process model. In terms of that model, we delineate the necessary assumptions for this methodology to yield approximately unbiased answers, and we provide means for testing some of those assumptions. We show how to design a series of PCRs to attain optimal precision of the estimate. We provide an algorithm for conducting the statistical analysis of the data, including a formula for a confidence interval for the unknown expected initial copy number.

Algorithms↗