The power of repetition in mastering cardiac auscultation.
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Clinical Competence↗
Biomedical subjects
Michael J Barrett
Publications and source records attributed to Michael J Barrett.
Comparability of segmented line regression models.
Segmented line regression models, which are composed of continuous linear phases, have been applied to describe changes in rate trend patterns. In this article, we propose a procedure to compare two segmented line regression functions, specifically to test (i) whether the two segmented line regression functions are identical or (ii) whether the two mean functions are parallel allowing different intercepts. A general form of the test statistic is described and then the permutation procedure is proposed to estimate the p-value of the test. The permutation test is compared to an approximate F-test in terms of the p-value estimation and the performance of the permutation test is studied via simulations. The tests are applied to compare female lung cancer mortality rates between two registry areas and also to compare female breast cancer mortality rates between two states.
Biometry↗
Malfunction of the automatic slope adjustment of the QT sensor in patients with normal QT intervals.
DDDR pacemakers with QT driven sensor algorithms may be susceptible to inappropriate pacemaker tachycardia when implanted into patients who have a relatively extended cardiac repolarization. The inability to detect and measure the QT interval at near maximum sensor rate, results in an inappropriate adjustment of the automatic QT slope. Triggering pacemaker induced tachycardia.
Adult↗
Mastering cardiac murmurs: the power of repetition.
BACKGROUND: The ability of medical students to recognize heart murmurs is poor (20%), and does not improve with subsequent years of training. A teaching method to improve this skill would be useful. STUDY OBJECTIVES: To determine whether intensive repetition of four basic cardiac murmurs improves auscultatory proficiency in medical students. DESIGN: Controlled intervention study. SUBJECTS: Fifty-one second-year medical students in an east coast medical school. INTERVENTIONS: Subjects were classified into three groups: (1) a monitored group, who listened to 500 repetitions of each murmur in a monitored setting, (2) an unmonitored group, who listened to 500 repetitions of each murmur in an unmonitored setting, and (3) a control group. All three groups were tested using a pretest and posttest methodology. MEASUREMENTS AND RESULTS: The 20 subjects in the monitored group improved from 13.5 +/- 9.8 to 85 +/- 17.6% following the intervention (mean +/- SD). Similarly, 21 students in the unmonitored group improved from 20.9 +/- 10.9 to 86.1 +/- 15.6%. Ten control students showed no significant improvement (24 +/- 21.7 to 32 +/- 22.5%). The differences between the two intervention groups and the control subjects was significant at p < 0.001 by analysis of variance. CONCLUSION: Five hundred repetitions of four basic cardiac murmurs significantly improved auscultatory proficiency in recognizing basic cardiac murmurs by medical students. These results suggest that cardiac auscultation is, in part, a technical skill.
Cardiology↗
Null association between prostate cancer and serum folate, vitamin B(6), vitamin B(12), and homocysteine.
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Aged↗
Toenail selenium concentration and lung cancer in male smokers (Finland).
BACKGROUND: The objective of this investigation was to evaluate the association between toenail selenium concentration and lung cancer risk in male smokers. METHODS: We conducted a nested case-control study within the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study cohort. This substudy included 250 randomly selected incident lung cancer cases and 250 controls matched on age (up to +/- 5 years), intervention group assignment, and date of randomization (+/- 15 days). Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using conditional logistic regression methods. Finland began fortification of agricultural fertilizers in the fall of 1984, increasing the dietary intake, plasma, and toenail selenium concentrations for the population. The present analyses were based on the calculated residual of toenail selenium after regressing it on date of randomization. The selenium residual and the interaction of the residual with date of randomization were included in models with smoking status and body mass index as covariates. RESULTS: We observed a suggestion of a protective association for higher selenium status among men who entered the trial early (when the range of selenium values included very low levels). The OR for men with adjusted toenail selenium concentrations at the 75th percentile compared to those with the lowest selenium concentrations ranged between 0.20 (0.09-0.44) for men randomized earliest in the trial and 0.61 (0.27-1.41) for men randomized in the fifth year. CONCLUSIONS: These results suggest that low selenium status may be associated with increased risk for lung cancer.
Aged↗