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Hospital cesarean delivery rates that are not adjusted for clinical risk factors may be biased, and mislead the public
EV IDE NCE-B ASED HE AL TH P OL I CY
Hospital cesarean delivery rates that are not adjusted for clinical risk factors may be biased, and mislead the public Aron DC, Harper DL, Shepardson LB, Rosenthal GE. Impact of risk-adjusting cesarean delivery rates when reporting hospital performance. JAMA 1998;279:1968d1972.
OBJECTIVE To compare hospital cesarean delivery rates before and after adjusting for clinical risk factors that increase likelihood of cesarean delivery. SETTING 21 hospitals (5 teaching; 16 non-teaching) in northeast Ohio, USA, from January 1993 to June 1995. METHOD Retrospective cohort study. LITERATURE REVIEW No explicit strategy; 44 references. PATICIPANTS 26,127 women without prior cesarean deliveries admitted for labor and delivery. Women undergoing therapeutic abortions, or who did not deliver at least one neonate weighing 500 g or more, were excluded. All study data were obtained from Cleveland Health Quality Choice, a regional coalition of employers, hospitals, and physicians to compare the quality of hospital-based services. In 11 hospitals, where the annual number of total deliveries was projected to be less than 1200, data were collected on all eligible admissions. In 10 hospitals, where the annual number of total deliveries was projected to be 1200 or more, data were collected on eligible admissions on days randomly selected by Cleveland Health Quality Choice.
Commentary This paper disappointed me. An enormous amount of work was involved in collecting data from over 26,000 patient records, extremely sophisticated statistical tests were used to develop a logistic regression model, and the net result was a change in the outlier status of 5 of the 21 hospitals studied. The mean cesarean section rate (CSR) was 15.9% with a range from 6.3 to 26.5%, and after adjustment the range was 8.4 to 22% . Women with a previous cesarian section were excluded and no attempt was made to look at rates of dystocia. While I agree that defining dystocia is difficult, the Task Force1 reported in 1978 that this diagnosis, along with repeat cesarean section and breech presentation, were the main factors that had led to the 3-fold increase in CSR from 1970. As the US Government2 has called for a reduction in the primary CSR to 12% and an increase in women allowed to attempt a vaginal birth after cesarian section (VBAC) by the year 2000, it seems a pity that some of this effort was not used to find out what proportion of women attempted VBAC and were successful. Such a figure would have helped users of the service and those paying for it. Studies have shown that at least two-thirds of women can deliver normally after cesarian section and, where the primary indication is breech presentation, 85% can do so.3 Should a technique that adjusts on the basis of a high CSR that is not based on good evidence (e.g. breech and twins) be used at all?4, 5 Would it not be a better strategy for purchasers of health care to set a rate of CSR,
^ 1999 Harcourt Publishers Ltd
OUTCOME MEASURES Hospital rankings observed and risk-adjusted cesarean delivery rates.
based
on
ANALYSIS Cesarean section rates were calculated for each hospital, with and without risk adjustment. Risk adjustment for 39 risk factors used multiple logistic regression. All data were abstracted from patients’ hospital records by medical records technicians. The rankings of the 21 hospitals using unadjusted and adjusted cesarean section rates were compared using the Spearman correlation coefficient. RESULTS The correlation between rankings using adjusted and unadjusted rates was poor (R"0.35, P"0.12). Whereas seven hospitals were classified as outliers on the basis of both unadjusted and adjusted rates, outlier status changed for five hospitals (24%); two changed from outliers to non-outliers, two changed from non-outliers to outliers, and one changed from an outlier with high rates to an outlier with low rates. AUTHORS’ CONCLUSIONS Cesarean delivery rates varied across hospitals in a single metropolitan region, and could be biased if clinical risk factors were not taken into account.
say 10%,6 and ask the providers to justify why their rate is higher before agreeing to pay for the extra cost? Wendy Savage The Medical Schools of St Bartholomew’s and the Royal London Hospitals, Queen Mary Westfield College, London, UK
Literature cited 1. Cesarean Childbirth. Task Force. US Institute of Health and Human Services. Washington: National Institutes of Health, 1981. 2. Healthy People 2000. Department of Health and Human Services. DHSS Pub No (PHS) 91-50212 Washington DC, 1991. 3. Rosen MG, Dickinson JC. Vaginal birth after cesarean: a meta-analysis of indicators for success. Obstetrics and Gynaecology 1990; 76: 865d869. 4. Hannah M, Hannah W. Caesarean section or vaginal birth for breech presentation at term. We need better evidence as to which is better. BMJ 1996; 312: 1433d1434. 5. Rhydstrom H, Ingenarsson I, Ohrlander S. Lack of correlation between a high caesarean rate and improved prognosis for low birth weight twins, Br J Obstet Gynaecol 1990; 97: 229d236. 6. Francome C, Savage W. Caesarean section in Britain and the United States 12% or 24%: is either the right rate? Soc Sci Med 1993; 37: 1199d1218.
Evidence-based Healthcare (1999) 3, 109
109
Hospital cesarean delivery rates that are not adjusted for clinical risk factors may be biased, and mislead the public Aron DC, Harper DL, Shepardson LB, Rosenthal GE. Impact of risk-adjusting cesarean delivery rates when reporting hospital performance. JAMA 1998;279:1968d1972.
OBJECTIVE To compare hospital cesarean delivery rates before and after adjusting for clinical risk factors that increase likelihood of cesarean delivery. SETTING 21 hospitals (5 teaching; 16 non-teaching) in northeast Ohio, USA, from January 1993 to June 1995. METHOD Retrospective cohort study. LITERATURE REVIEW No explicit strategy; 44 references. PATICIPANTS 26,127 women without prior cesarean deliveries admitted for labor and delivery. Women undergoing therapeutic abortions, or who did not deliver at least one neonate weighing 500 g or more, were excluded. All study data were obtained from Cleveland Health Quality Choice, a regional coalition of employers, hospitals, and physicians to compare the quality of hospital-based services. In 11 hospitals, where the annual number of total deliveries was projected to be less than 1200, data were collected on all eligible admissions. In 10 hospitals, where the annual number of total deliveries was projected to be 1200 or more, data were collected on eligible admissions on days randomly selected by Cleveland Health Quality Choice.
Commentary This paper disappointed me. An enormous amount of work was involved in collecting data from over 26,000 patient records, extremely sophisticated statistical tests were used to develop a logistic regression model, and the net result was a change in the outlier status of 5 of the 21 hospitals studied. The mean cesarean section rate (CSR) was 15.9% with a range from 6.3 to 26.5%, and after adjustment the range was 8.4 to 22% . Women with a previous cesarian section were excluded and no attempt was made to look at rates of dystocia. While I agree that defining dystocia is difficult, the Task Force1 reported in 1978 that this diagnosis, along with repeat cesarean section and breech presentation, were the main factors that had led to the 3-fold increase in CSR from 1970. As the US Government2 has called for a reduction in the primary CSR to 12% and an increase in women allowed to attempt a vaginal birth after cesarian section (VBAC) by the year 2000, it seems a pity that some of this effort was not used to find out what proportion of women attempted VBAC and were successful. Such a figure would have helped users of the service and those paying for it. Studies have shown that at least two-thirds of women can deliver normally after cesarian section and, where the primary indication is breech presentation, 85% can do so.3 Should a technique that adjusts on the basis of a high CSR that is not based on good evidence (e.g. breech and twins) be used at all?4, 5 Would it not be a better strategy for purchasers of health care to set a rate of CSR,
^ 1999 Harcourt Publishers Ltd
OUTCOME MEASURES Hospital rankings observed and risk-adjusted cesarean delivery rates.
based
on
ANALYSIS Cesarean section rates were calculated for each hospital, with and without risk adjustment. Risk adjustment for 39 risk factors used multiple logistic regression. All data were abstracted from patients’ hospital records by medical records technicians. The rankings of the 21 hospitals using unadjusted and adjusted cesarean section rates were compared using the Spearman correlation coefficient. RESULTS The correlation between rankings using adjusted and unadjusted rates was poor (R"0.35, P"0.12). Whereas seven hospitals were classified as outliers on the basis of both unadjusted and adjusted rates, outlier status changed for five hospitals (24%); two changed from outliers to non-outliers, two changed from non-outliers to outliers, and one changed from an outlier with high rates to an outlier with low rates. AUTHORS’ CONCLUSIONS Cesarean delivery rates varied across hospitals in a single metropolitan region, and could be biased if clinical risk factors were not taken into account.
say 10%,6 and ask the providers to justify why their rate is higher before agreeing to pay for the extra cost? Wendy Savage The Medical Schools of St Bartholomew’s and the Royal London Hospitals, Queen Mary Westfield College, London, UK
Literature cited 1. Cesarean Childbirth. Task Force. US Institute of Health and Human Services. Washington: National Institutes of Health, 1981. 2. Healthy People 2000. Department of Health and Human Services. DHSS Pub No (PHS) 91-50212 Washington DC, 1991. 3. Rosen MG, Dickinson JC. Vaginal birth after cesarean: a meta-analysis of indicators for success. Obstetrics and Gynaecology 1990; 76: 865d869. 4. Hannah M, Hannah W. Caesarean section or vaginal birth for breech presentation at term. We need better evidence as to which is better. BMJ 1996; 312: 1433d1434. 5. Rhydstrom H, Ingenarsson I, Ohrlander S. Lack of correlation between a high caesarean rate and improved prognosis for low birth weight twins, Br J Obstet Gynaecol 1990; 97: 229d236. 6. Francome C, Savage W. Caesarean section in Britain and the United States 12% or 24%: is either the right rate? Soc Sci Med 1993; 37: 1199d1218.
Evidence-based Healthcare (1999) 3, 109
109