Biomedical subjects

L W Dicker

Publications and source records attributed to L W Dicker.

6 recordsLinked to original sources

PubMed2000

Impact of switching laboratory tests on reported trends in Chlamydia trachomatis infections.

Improvements in the sensitivity and specificity of laboratory testing methods for Chlamydia trachomatis infections in recent years have created potential problems with interpreting data on chlamydia prevalence trends. A switch to a more sensitive test can result in an increase in chlamydia positivity even with no increase in the true disease prevalence. To examine the impact of switching laboratory testing methods on chlamydia positivity trends among women, the authors analyzed data from chlamydia screening programs in family planning clinics in two geographic areas of the United States. Data from 7,287 tests performed in Philadelphia, Pennsylvania, indicated a 46% increase in positivity (from 4.1% to 6.0%) when the clinics switched from a nucleic acid probe assay to a ligase chain reaction test. Data from 35,306 tests performed in Oregon and Washington State laboratories showed a 21% increase in positivity (from 3.3% to 4.0%) when clinics switched from a direct immunofluorescent antibody testing procedure to an enzyme immunoassay with negative gray zone confirmation. These increases were within ranges consistent with the variability of the testing methods and occurred primarily in asymptomatic women and in women over age 20 years. Any switch in laboratory testing methods must be considered when interpreting data on chlamydial infection trends.

Adult↗

PubMed1999

A metaregression analysis of the dose-response effect of aspirin on stroke.

BACKGROUND: We evaluated whether the risk of stroke depends on aspirin dose in patients with a previous transient ischemic attack or stroke. METHODS: We conducted a metaregression analysis of stroke by using published randomized, placebo-controlled trials. We analyzed studies of patients who had recently had a transient ischemic attack or stroke (ie, secondary prevention). We abstracted data on the treatment regimen and stroke. To evaluate the dose-response relationship, we conducted a metaregression analysis of study-specific risk ratios by means of weighted linear regression. RESULTS: Eleven randomized, placebo-controlled trials contributed a total of 5228 patients randomized to aspirin only and 4401 patients randomized to placebo only. The slope of the dose-response curve was virtually flat across a wide range of aspirin doses from 50 to 1500 mg/d (P = .49 for test of slope not =0). Summarizing across studies, aspirin decreases the risk of stroke by about 15% (risk ratio, 0.85;95% confidence interval, 0.77-0.94). CONCLUSIONS: Aspirin reduces the risk of stroke by approximately 15%, and this effect is uniform across aspirin doses from 50 to 1500 mg/d. The lowest effective aspirin dose has not yet been identified, but it could be lower than 50 mg/d.

Aged↗

PubMed1999

The risk of serious cardiac arrhythmias among cisapride users in the United Kingdom and Canada.

PURPOSE: Serious, although rare, ventricular arrhythmias and deaths have been reported in patients taking cisapride monohydrate. Without quantification of the risk involved, it is impossible to develop rational therapeutic guidelines. SUBJECTS AND METHODS: Arrhythmic events (sudden deaths and other events compatible with serious ventricular arrhythmias) were sought among 36,743 patients prescribed cisapride in the United Kingdom and Saskatchewan, Canada. Prescriptions and cases were identified from computerized medical claims data and physicians' office records. We compared rates of events between periods of recent cisapride use and nonrecent use, using cohort analysis. Potential confounding factors, including concomitant treatment with agents that inhibit CYP3A4 metabolism or that prolong the QT interval, were assessed in a nested case-control study. RESULTS: In the cohort analysis, the incidence of the arrhythmic events was 1.6 times greater (95% confidence interval [CI]: 0.9 to 2.9) in periods of recent use. With adjustment for clinical history, use of CYP3A4 inhibitors, and use of drugs that prolong the QT interval, the odds ratio for cisapride and cardiac outcomes was 1.0 (95% CI: 0.3 to 3.7). There was no identifiable increase in risk when cisapride was dispensed at about the same time as QT-prolonging drugs or CYP3A4 inhibitors. QT-prolonging agents were associated with a 2.5-fold increase in the risk of arrhythmic events (95% CI: 1.1 to 5.8). CONCLUSIONS: Serious rhythm disorders were not associated with cisapride use, although the upper confidence bounds do not rule out an increase in risk.

Adolescent↗

PubMed1998

Chlamydia positivity versus prevalence. What's the difference?

BACKGROUND: Data on chlamydia screening collected as part of Regional Infertility Prevention Projects often do not include personal identifiers, therefore repeat tests for patients during a year cannot be identified. Consequently, positivity is calculated and used to monitor chlamydia prevalence. GOALS: To assess how well positivity can estimate prevalence in family planning and sexually transmitted disease (STD) clinic settings. STUDY DESIGN: Analyzed data from chlamydia screening programs in three geographic areas of the United States that used unique patient identifiers. RESULTS: The relationship between positivity and prevalence is related to both the percentage of tests that are repeat tests and the percentage of repeat tests that are positive. On average, the percentage of positive repeat tests was the same as or higher than prevalence in family planning clinics; thus, positivity was the same as or higher than prevalence. In STD clinics, the percentage of positive repeat tests was consistently lower than prevalence; thus, positivity underestimated prevalence. However, the absolute difference between positivity and prevalence was less than 0.5% in family planning and STD clinics. CONCLUSIONS: Positivity can be used to monitor chlamydia prevalence in women screened in family planning and STD clinic settings.

Chlamydia Infections↗

PubMed1998

Human immunodeficiency virus partner notification. Cost and effectiveness data from an attempted randomized controlled trial.

OBJECTIVE: Determine the cost and effectiveness of partner notification for human immunodeficiency virus (HIV) infection. METHODS: Persons testing HIV positive in three areas were randomly assigned one of four approaches to partner notification. Analysis plans changed because disease intervention specialists notified many partners from the patient referral group. We dropped the patient referral group and combined the others to assess the cost and effectiveness of provider referral. RESULTS: The 1,070 patients reported 8,633 partners. Of those 1,035 were located via record search or in person. A previous positive test was reported by 248 partners. Of the 787 others, 560 were tested: 438 were HIV negative and 122 were newly identified as HIV positive. The intervention specialist's time totaled 197 minutes per index patient. The cost of the intervention specialist's time, travel, and overhead was $268,425: $251 per index patient, $427 per partner notified, or $2,200 per new HIV infection identified. No demographic characteristic of the index patient strongly predicted the likelihood of finding an infected partner. CONCLUSION: We could not compare the effectiveness of different partner notification approaches because of frequent crossover between randomized groups. The cost of partner notification can be compared with other approaches to acquired immunodeficiency syndrome prevention, but the benefits are not easily measured. We do not know the number of HIV cases prevented or the value of fulfilling the ethical obligation to warn partners of a potential threat to their health.

Adolescent↗

PubMed1997

Partner notification for syphilis: a randomized, controlled trial of three approaches.

OBJECTIVE: To determine the cost and effectiveness of three approaches to partner notification for infectious syphilis. STUDY DESIGN: People with syphilis were randomly assigned to: (1) notification of partners by patients themselves within 2 days or disease intervention specialists would notify them; (2) immediate notification by intervention specialist; or (3) immediate notification by intervention specialists, who had the option of drawing blood in the field. Costs of intervention specialists' time, travel, and overhead were measured. Intention-to-treat analysis measured outcomes per randomized index patient. RESULTS: From December, 1990 through March, 1993, 1,966 index patients with syphilis (primary 9%; secondary 18%; and early latent 73%) were randomized in Broward County (Ft. Lauderdale), Florida (1,191); Tampa, Florida (569); and Paterson, New Jersey (206). Index patients reported 11,272 potentially exposed partners and sufficient information to initiate investigations for 2,761. Of these, 2,236 were located, 367 had newly identified infections, and 870 others received preventive treatment. The three partner notification approaches had similar success locating partners (1.1-1.2 per index patient) and treating partners (0.61-0.67 per index). The cost was $317 to $362 per partner treated; the optimal strategy differed by study site. CONCLUSIONS: Partner notification identified many infected and potentially infected people. The cost and effectiveness of the three types of provider notification were similar. Alternative approaches are needed to reach infected partners who could not be notified.

Adult↗