The contribution of the case-control approach to vaccine evaluation: Pneumococcal and Haemophilus influenzae type B PRP vaccines.

Case-control studies have had an increasing role in the postlicensure evaluation of vaccine efficacy. We review the contribution of case-control studies to the evaluation of vaccines for Streptococcus pneumoniae (pneumococcus) and Haemophilus influenzae type b (Hib) and compare these studies with clinical trials of these vaccines. We located one clinical trial and eight case-control studies of Hib PRP vaccine efficacy and three clinical trials and four case-control studies of pneumococcal vaccine efficacy. The pooled estimate of Hib PRP vaccine efficacy based on the case-control studies (0.38, 95% CL = 0.15-0.55) was lower than the efficacy of the clinical trial conducted in Finland (0.8, 95% CL = 0.57-0.98). The pooled estimate of pneumococcal vaccine efficacy based on the case-control studies (0.56, 95% CL = 0.44-0.66) was also lower than the pooled efficacy of the South African clinical trials (0.79, 95% CL = 0.69-0.86). Although the clinical trials provided crucial evidence that these vaccines worked in selected international settings, the direct evidence of efficacy in the United States rests largely on the case-control results. The utility of the case-control approach is supported.

Empirical comparison of the results of randomized controlled trials and case-control studies in evaluating the effectiveness of screening mammography.

The gold standard for evaluating screening programs is the randomized controlled trial (RCT). Case-control studies are easier to perform but their role in this area is controversial. The purpose of this article is to compare empirically the results of RCTs and case-control studies conducted to evaluate the efficacy and effectiveness of screening mammography and examine possible explanations for differences in their results. We located eight RCTs and five case-control studies of screening mammography. For women aged 40-74 years at screening, comparison of the summary risk estimates of the RCTs (0.76, 95% CI: 0.69-0.83) with that of the case-control studies (0.44, 95%, CI: 0.38-0.50) showed RCTs to have a significantly higher summary risk estimate than case-control studies (ratio = 1.74, 95% CI: 1.48-2.04). It is notable that the RCTs were compromised in most instances by low compliance rates (50-80%) in the treatment groups and by significant use of screening in the control groups (20-30%). Adjustment of the RCT results for these cross-overs yields results that are in reasonable agreement with the summary estimate for the case-control studies. These findings support the use of case-control studies to estimate the efficacy of mammographic screening where RCTs are not feasible. They suggest that the efficacy of mammography in women aged 50 years and above is somewhat greater than the effectiveness measured by the intent-to-treat analysis of RCTs.

Factors associated with research productivity in family practice residencies.

BACKGROUND: Research productivity and the associated features of research productivity in family practice residencies have not been well described. The objectives of this study are to describe residency research productivity and identify the set of independent factors that best characterize programs at various levels of productivity. METHODS: A 23-item survey was mailed to 226 randomly selected family practice residency directors. The survey included items on program demographics, mentoring, resident and faculty research activities, and program research resources. Factor and discriminant analyses were performed to identify the major independent factors associated with productivity. RESULTS: A total of 154 completed surveys were received for a response rate of 68%. Based on a cross tabulation of grants per program and publications per faculty, 22% of programs had high productivity, 46% had medium productivity, and 32% had low productivity. The significant factors of mentor support, amount of research activity, and program size contributed independently to the classification of programs by relative level of research productivity. These associations remained significant when university programs were excluded. CONCLUSIONS: Family practice residencies with relatively higher research productivity are more likely to have three characteristics than lower productivity programs: availability of a research mentor, more faculty research activities, and larger program size.

Telemedicine precepting in a family practice center.

BACKGROUND AND OBJECTIVES: This study assessed the feasibility, reliability, and acceptability of video teleconference precepting of residents practicing in rural sites. METHODS: Precepting encounters were conducted between faculty at our home-base family practice center and third-year residents at a rural site. Full audio and video teleconferencing equipment was used; data was transmitted by fractional T1 lines. Residents and faculty recorded patient demographics, rated the technical quality of the encounter, and noted equipment problems during encounters. RESULTS: Video teleconferencing was used for 137 patient encounters, which was 10% of all encounters. The self-reported technical quality of the encounter was acceptable (all 4 dimensions of quality rated a median score of 4 out of 5). Minor transmission or equipment problems were noted 20% of the time by residents. Use of teleconferencing diminished considerably over the 6-month period of the study. Most cases precepted by teleconferencing involved uncomplicated acute illnesses. CONCLUSIONS: Telemedicine precepting was technically feasible, generally reliable, and initially acceptable to the third-year residents. However, the cases precepted were mostly acute illnesses, and use of telemedicine for precepting diminished over time.