Table 4.

 Characteristics of obstetrics sample

Characteristics	Obstetricians involved in deliveries
No of physicians	1625
No of physician years	10 358
No of deliveries (caesarean and vaginal)	1 518 702
No of deliveries per physician year	147
No of caesarean deliveries	224 850
Mean caesarean delivery rate (%)	14.8
No of malpractice claims	496
No of malpractice claims per obstetrician year (%)	4.8
Mean adjusted caesarean rate per obstetrician (%):*
Physicians with a malpractice claim	13.7
Physicians without a malpractice claims	15.2
P value for difference†	<0.001

*Constructed by estimating a patient level logistic model of caesarean delivery as a function of mother’s age, race, year, and county fixed effects, and obstetrician indicators. Deliveries that involved clinical contraindications to vaginal delivery (for example, fetal distress, breech presentation, previous caesarean) were excluded. Caesarean rates for obstetricians with a malpractice claim reflect the mean rate per obstetrician in the year previous to an incident among physicians with a malpractice claim (that is, cases). Caesarean rates for obstetricians without a malpractice claim reflect the mean rate per obstetricians in all years among obstetricians with a malpractice claim (that is, controls).

†Difference in means between cases and controls.