Search PubMed⌕ Search

Biomedical subjects

Darryl Davis

Publications and source records attributed to Darryl Davis.

2 recordsLinked to original sources

Reasons for escalating pacemaker implants.

Surveys of pacing practice have shown a steady increase in pacemaker implantation rates in the past 15 years, despite no major changes in United States guidelines for permanent pacing. There are no data to explain why this is occurring. In this study, records were extracted from the National Hospital Discharge Survey to investigate this. There were 3 major findings. First, age-adjusted implantation rates increased progressively over the study period from 370 per million in 1990 to 612 per million in 2002. Second, it was found that the escalating implantation rate is attributable to increasing implantation for isolated sinus node dysfunction (SND). Implantation for SND increased significantly over the study period (by 102%), whereas implantation for all other indications did not. The increasing implantation for SND is due primarily to the increasing prevalence of SND, with a lesser increase in implantation rate relative to prevalence rate. The third major finding of this study is that there has been a progressive relative and absolute increase in the dual-chamber implantation rate. In 2002, 82.8% of all initial pacemaker implantations were dual-chamber devices. Furthermore, the National Hospital Discharge Survey data indicate that the major randomized pacing trials seem to have had no impact on pacing practice in the United States. In conclusion, age-adjusted implantation rates increased progressively over the study period. This escalating implantation rate is primarily attributable to increasing implantation for SND.

Age Factors↗

Time-dependent bias was common in survival analyses published in leading clinical journals.

OBJECTIVE: In survival analysis, "baseline immeasurable" time-dependent factors cannot be recorded at baseline, and change value after patient observation starts. Time-dependent bias can occur if such variables are not analyzed appropriately. This study sought to determine the prevalence of such time-dependent bias in highly-cited medical journals. STUDY DESIGN AND SETTING: We searched Medline databases to identify all observational studies that used a survival analysis in American Journal of Medicine, Annals of Internal Medicine, Archives of Internal Medicine, British Medical Journal, Chest, Circulation, Journal of the American Medical Association, Lancet, and New England Journal of Medicine between 1998 and 2002. Studies with "baseline immeasurable" time-dependent factors were susceptible to time-dependent bias if a time-dependent covariate analysis was not used. RESULTS: Of 682 eligible studies, 127 (18.6%, 95% CI 15.8-21.8%) contained a "baseline immeasurable" time-dependent factor and 52 (7.6% [5.8-9.9%] of all survival analyses/40.9% [32.3-50.0%] of studies with a time-dependent factor) were susceptible to time-dependent bias. In 35 studies (5.1% [3.7-7.1%]/27.6% [20.5-35.9%]), the bias affected a variable highlighted in the study abstract and correction of the bias could have qualitatively changed the study's conclusion in over half of studies. CONCLUSION: In medical journals, time-dependent bias is concerningly common and frequently affects key factors and the study's conclusion.

Bias↗