Search

For the 10% to 15% of American married couples who experience reproductive problems, in vitro fertilization (IVF) is the leading technologically advanced treatment procedure. However, IVF's expense may prevent many couples from receiving treatment, and those who are treated may take an overly aggressive approach to reduce the probability of failure. Aggressive treatment, which occurs through an increase in the number of embryos transferred during IVF, can lead to medically dangerous multiple births. We evaluated the principle policy proposal-insurance mandates-for improving IVF access and outcomes. We used data from US markets during 1995-2003 to show that broad insurance mandates for IVF result in not only large increases in treatment access but also significantly less aggressive treatment. More limited insurance mandates, which may apply to a subset of insurers or provide weaker guidelines for insurer behavior, generally have little effect on IVF markets.

This paper assesses the causal impact of late-term (8th month) maternal smoking on birthweight using data from a randomized clinical trial, in which some women were encouraged not to smoke, while others were not. The estimation of treatment effects in this case is made difficult as a result of the presence of non-compliers, women who would not change their smoking status, regardless of the receipt of encouragement. Because these women are not at risk of changing treatment status, treatment effect distributions may be difficult to construct for them. Consequently, the paper focuses on obtaining the distribution of treatment impacts for the sub-set of compliers found in the data. Because compliance status is not observed for all subjects in the sample, a Bayesian finite mixture model is estimated that recovers the treatment effect parameters of interest. The complier average treatment effect implies that smokers give birth to infants weighing 348 g less than those of non-smokers, on average, although the 95% posterior density interval contains zero. The treatment effect is stronger for women who were moderate smokers prior to pregnancy, implying a birthweight difference of 430 g. However, the model predicts that only about 22% of the women in the sample were at risk of changing their smoking behaviour in response to encouragement to quit. Copyright © 2001 John Wiley & Sons, Ltd.

The fraction of US Medicare recipients enrolled in health maintenance organizations (HMOs) has increased substantially over the past 10 years. However, the impact of HMOs on health care costs is still hotly debated. In particular, it is argued that HMOs achieve cost reduction through 'cream-skimming' and enrolling relatively healthy patients. This paper develops a Bayesian panel data tobit model of HMO selection and Medicare expenditures for recent US retirees that accounts for mortality over the course of the panel. The model is estimated using Markov Chain Monte Carlo (MCMC) simulation methods, and is novel in that a multivariate t-link is used in place of normality to allow for the heavy-tailed distributions often found in health care expenditure data. The findings indicate that HMOs select individuals who are less likely to have positive health care expenditures prior to enrollment. However, there is no evidence that HMOs disenrol high cost patients. The results also indicate the importance of accounting for survival over the panel, since high mortality probabilities are associated with higher health care expenditures in the last year of life.

This paper investigates the surgical volume-outcome relationship for patients undergoing hip fracture surgery in Quebec between 1991 and 1993. Using a duration model with multiple destinations which accounts for observed and unobserved (by the researcher) patient characteristics, our initial estimates show that higher surgical volume is associated with a higher conditional probability of live discharge from the hospital. However, these results reflect differences between hospitals rather than differences within hospitals over time: when we also control for differences between hospitals that are fixed over time, hospitals performing more surgeries in period t + 1 than in period t experience no significant change in outcomes, as would be predicted by the 'practice makes perfect' hypothesis. The volume-outcome relationship for hip fracture patients thus appears to reflect quality differences between high and low volume hospitals.

For the 10% to 15% of American married couples who experience reproductive problems, in vitro fertilization (IVF) is the leading technologically advanced treatment procedure. However, IVF's expense may prevent many couples from receiving treatment, and those who are treated may take an overly aggressive approach to reduce the probability of failure. Aggressive treatment, which occurs through an increase in the number of embryos transferred during IVF, can lead to medically dangerous multiple births. We evaluated the principle policy proposal-insurance mandates-for improving IVF access and outcomes. We used data from US markets during 1995-2003 to show that broad insurance mandates for IVF result in not only large increases in treatment access but also significantly less aggressive treatment. More limited insurance mandates, which may apply to a subset of insurers or provide weaker guidelines for insurer behavior, generally have little effect on IVF markets.