Sunday, August 14, 2005

AIDS in Minority Communities: The Role of Incarceration

Two Berkeley economists have written an intriguing paper documenting that an unintended consequence of increased black male incarceration rates is higher AIDS rates for African-American men and women.

Rucker Johnson and Steven Raphael’s new empirical paper titled “The Effects of Male Incarceration Dynamics on AIDS Infection Rates among African-American Women and Men” uses data from 1982 to 2001. People are divided up into different cells depending on what state they live in, their age, race and sex. The authors use several data sets to calculate for each cell (a state/age category/race category/sex category) the AIDS rate and the imprisonment rate in previous years. Regression techniques are used to study the relationship between these two variables.

Why could there be a causal relationship between increased incarceration rates and later increases in AIDS rates? To quote the authors:

“An increase in male incarceration rates may affect HIV/AIDS infection rates among inmates and members of the community at large through several channels. First, the relatively high concentration of HIV-positive people in prison (Hammett et. al. 2002) coupled with risk behavior among inmates (Krebs 2002, Swartz et. al. 2004) may accelerate the transmission rate of the disease among the incarcerated and among non-incarcerated members of the sexual networks of former inmates. Second, the temporal dynamics of incarceration, characterized by brief incarceration spells and the cycling in and out of institutions, may increase the degree of concurrent sexual relationships (sexual relationships that overlap in time) among inmates and their non-institutionalized partners (Adimora and Schoenbach 2005). This is a factor known to augment the risk of contracting and spreading sexually transmitted diseases. In addition, spells of incarceration may hasten the dissolution of sexual relationships, enlarging the total lifetime number of sex partners among inmates and their partners. An increase in incarceration rates may be viewed as an exogenous shock to an affected individual or group’s sexual-relationship market (in much the same way economists traditionally conceive of marriage markets (Becker 1981)). In particular, male incarceration lowers the sex ratio (male-to-female), abruptly disrupts the continuity of heterosexual relationships, and increases exposure to homosexual activity for incarcerated males—all of which may have far-reaching implications for an individual or group’s AIDS infection risk. Given the relatively high rate of incarceration among black men, all these avenues of HIV/AIDS transmission are likely to have disproportionate effects on the AIDS infection rates of black women and men.”

Their empirical results support their hypothesis.

“Thus far, we have documented strong partial correlations between the rate at which men and women become infected with full blown AIDS and lagged values of the incarceration rate for males in one’s demographic group defined by age, race, year, and state of residence. These correlations persist when we focus only on variation occurring within sexual relationship markets over time and after removing race-, age-, and state-specific year-to-year changes in both AIDS infection and incarceration rates. These partial correlations are highly significant and the implied lagged effects of incarceration parallel estimates of the pre-1996 AIDS incubation period distribution. Moreover, the effect sizes suggest that much of the racial differential in AIDS infection rates are attributable to historical differences in the rates at which black men are incarcerated.”

This paper documents an important public health externality exacerbated by prison terms. One wonders how many fewer AIDS cases there would be in a world where drugs were legalized?