- © 2004 Canadian Medical Association or its licensors
Our article showing that maternal and newborn outcomes at delivery were similar for physicians with high and low obstetric volume1 generated speculation among our colleagues that perhaps volume and outcomes were correlated with experience. To answer this question, we re-analyzed the original data to determine if a proxy measure of experience — years in practice — was associated with maternal and infant outcomes.
We divided the family physicians in our study into 3 groups on the basis of date of graduation from medical school: 1950 to 1977 (49 doctors, 1403 births), 1978 to 1987 (46 doctors, 1572 births) and 1988 to 1995 (53 doctors, 1458 births). We redid the logistic regression as described in our paper,1 using years of practice and adjusting for delivery volume and maternal and fetal characteristics. We used ≤ 7 as the cutoff for 5-minute Apgar scores in both analyses.
There were statistically significant differences in parity and demographic characteristics of the mothers according to family physicians' time since graduation. Physicians with more years since graduation had more multiparous women in their practices than physicians with fewer years since graduation (52% v. 44%, p < 0.001). The proportion of white women was also different among physician groups (40% for the group with the most years since graduation, 51% for the intermediate group and 38% for the group with the fewest years since graduation, p < 0.001). Physicians with the most years since graduation attended more deliveries for women over 35 years of age than physicians with the fewest years since graduation (23% v. 19%, p = 0.002).
Our original paper1 showed no difference in maternal and infant outcomes by physician volume. When we factored in years since graduation, we found significantly higher rates of admission to any special care nursery and lower 5-minute Apgar scores for physicians with fewer years since graduation than for physicians with more years since graduation at our original level of statistical significance of 0.05, after adjustment for physician delivery volume, maternal demographic characteristics and maternal risk factors (Table 1). However, delivery volume was still not a statistically significant predictor of outcomes. Therefore, it seems that years of experience has a greater effect on outcomes than volume of deliveries. We believe that in analyzing the data according to physician experience, we are considering an outcome of possible clinical importance because, although Apgar scores are subjective, the responsible family physician requires a pediatrician to support an admission to a special care nursery. But because the odds ratios are not large and the cutoff level of significance is only 0.05, it would be prudent not to overstate the association between experience and newborn outcome. We suggest that when researching the outcome of birth according to delivery volume or when addressing other important outcomes in physician maternity and newborn practice, experience as indicated by years since graduation or other proxies should be taken into consideration. The recommendation of the Society of Obstetricians and Gynaecologists of Canada, the College of Family Physicians of Canada and the Society of Rural Physicians of Canada on number of births to maintain competence still stands:2 that is, there is no minimum number of births recommended to maintain competency. The consistency in outcomes by delivery volume in our study is reassuring, and we believe it is a result of ongoing professional development and quality assurance programs in our hospital. However, our results can be considered valid only for highly resourced centres such as ours.
Ann Kelly Departments of Health Care and Epidemiology and of Family Practice University of British Columbia Vancouver, BC Michael C. Klein Department of Family Practice University of British Columbia Vancouver, BC Janusz Kaczorowski Departments of Family Medicine and of Clinical Epidemiology and Biostatistics McMaster University Hamilton, Ont. Stefan Grzybowski Department of Family Practice University of British Columbia Vancouver, BC