Medical interventions among pregnant women in fee-for-service and managed care insurance: a propensity score analysis

Abstract

This paper extends earlier research on the effect of managed care on the receipt of four medical interventions for pregnant women: ultrasound, induction/stimulation of birth, electronic fetal monitor, and Caesarean delivery. Propensity score methods are used to account for sample selection issues regarding insurance choice. Managed care enrollees are more likely to receive an ultrasound, which may be indicative of receiving better prenatal care. Managed care plans reduce the rate of Caesarean deliveries, but such limitations may be beneficial given the substantial medical evidence that Caesarean deliveries are over-utilized. The results indicate that insurance coverage does influence treatment intensity, but that utilization controls and provider financial incentives do not adversely affect care for pregnant women.

Notes

¹ One exception is Currie and Gruber (2001), who examined the effect of Medicaid expansions during the early 1990s on utilization of the same four procedures.

² Rosenbaum and Rubin (1983) proposed using propensity scores to adjust for pre-treatment differences when there are two treatment groups. Imbens (2000) extends the method to the multiple treatment case. Foster (2003) presents a nice illustration of using multiple treatment propensity scores in health services research.

³ There also exists international evidence that insurance affects the provision of Caesarean deliveries. Mossialos et al . (2005) found that Caesarean deliveries are 20% more likely when the woman has private health insurance.

⁴ While not comparing managed care with fee-for-service insurances, Berger and Messer (2002) found that the share of national health expenditures from public sources was associated with increased mortality rates. Decker (2000) found that the introduction of the Medicaid program led to an increase in births to single women.

⁵ Births occurring in another state or country, not occurring in a hospital, or which cannot be matched to the SPARCS data are eliminated. Also, data from New York City were not available since NYC maintains its own vital records department.

⁶ Self-insured or self-pay patients are those patients for which there is no known insurance coverage. These could be either individuals who do not have coverage through their employer, who cannot afford coverage, affluent individuals who choose not to purchase insurance, or possibly individuals who have a benefactor who is taking the responsibility for the medical costs. Although the method of payment can be changed at a later date, these changes would not impact the provider's choice of procedure(s) at the time.

⁷ Expectant mother's medical risk factors include anemia, mellitus diabetes, genetic diseases, genital herpes, heart disease, hemoglobinopathy, hepatitis b, chronic hypertension, previous low birth-weight infant, chronic lung disease, macrosomia or previous infant >4000 g, previous pre-term infant, renal disease, RH sensitized, seizure disorders, previous spontaneous fetal death, thrombophlebitis, thyroid condition, gestational diabetes, in vitro fertilization, other fertilization treatment, hydramnios/oligohydramnios, pregnancy related hypertension, preeclampsia, eclampsia, incompetent cervix, acute lung disease, rubella, syphilis, other sexually transmitted disease, tuberculosis, uterine bleeding, viral disease, and other medical risk factor. Medical complications during labour or delivery are abruptio placenta, cephalopelvic disproportion, chorioamnionitis, coagulation defects, cord conditions, cord prolapse, failure to progress, fetal distress, fever, postpartum hemorrhage, cervical or vaginal lacerations, marginal sinus rupture, meconium particulate or moderate/heavy, non-vertex presentation, placenta previa, precipitous labor, prolonged rupture membrane (>12 h), premature rupture membrane (>1 h and <12 h), prolonged labour, retained placenta, seizures, uterine atony and other complications. Non-medical risk factors include smoking, alcohol use, drug use, mother's weight at delivery and weight gain during pregnancy.

⁸ Whereas we know the type of insurance coverage, the data do not indicate whether the insurance is a group or nongroup plan. Huttin (1997) found different patterns of prescription drug use enrollees in group and nongroup plans.

⁹ Insurance type is considered to be a choice variable for consumers, but Thurston (2002) finds that physician contracting with HMOs partially depends on geographic factors such as state tax rates. Thus, the extent of provider networks may differ across states, affecting the choices perceived by consumers.

¹⁰ The remaining procedures (ultrasound during delivery, fetal monitor, inducement/stimulation, and Caesarean delivery) are not mutually exclusive. Nor is one procedure linked with the performance of another procedure. For example, an induced delivery may not be successful leading to a Caesarean delivery. In other cases, only one of the procedures will be performed. As such, separate logit equations are estimated for each procedure treating each as an independent decision made by providers and patients.

¹¹ Ahern et al . (1996) considered HMO efficiency in providing services, and how service provision depends on HMO ownership. The authors found that HMOs owned by physicians tend to use more physician services, but that hospital-owned HMOs tend to use more inpatient services. Roland et al . (2004) examined commercial HMO premiums. Premiums are lower when there are more HMOs serving an area, especially among for-profit HMOs. Employer bargaining power is greater and premiums lower when the HMO has a higher ratio of administrative-to-total expenses.

¹² Some ultrasounds may also be performed during delivery, especially for certain complications and prior to some Caesarean deliveries. In addition, an ultrasound may be performed for some post-term pregnancies. Over 96% of the ultrasounds reported in our data were performed prior to labour/delivery.

¹³ It would be preferable to examine medically indicated and elective induction and stimulation separately, but the data do not contain the reason for receiving the procedure(s).

¹⁴ See Hornbuckle et al . (2000) for a meta-analysis of the link between EFM usage and perinatal mortality.

¹⁵ Computed as the difference in the marginal effects for fee-for-service and managed care BCBS plans. Marginal effects are computed as the difference in predicted probabilities between the relevant insurance category and those enrolled in commercial fee-for-service insurance with the remaining variables set to the sample means.