Question

Comparing Measures of Disease Frequency

The homeless are a vulnerable population with limited access to health care and poor health outcomes. Boston Health Care for the Homeless Program (BHCHP) analyzed deaths among homeless adults who were seen at their program from 1/1/2003 through 12/31/2008 (Baggett et al., 2014). A total of 1,302 deaths occurred during the observation period among the study population of 28,033 individuals. Mortality rates during 2003-2008 were compared to an earlier mortality study of homeless adults seen by BHCHP during 1988-1993 (Hwang et al., 1997). In the earlier cohort, there were 606 deaths among 17,292 individuals. Below are the demographic characteristics of participants in the two studies.

	1988-1993 Study N= 17,292		2003-2008 Study N=28,033
	Percent
Sex Male Female	68 32	66 34
Age 18-24 25-44 45-64 >=65	9 62 25 4	13 49 35 3
Race White Black Hispanic Other	45 36 17 2	43 29 19 9

1. Describe the demographic characteristics of the two study populations. Are there any meaningful differences?

2. The two studies collected only demographic data on the study participants. Suppose that you could have interviewed participants at enrollment to gather information on their illicit drug use. Exactly what information would you obtain on this behavior, and how would you summarize the data into categories for analysis? Be sure to specify your exposure and referent groups.

Answer 1

1. The ratio of male and female participants is almost same in both the studies but there seems a significant difference in terms of the participants of age groups 18-24 and 25-44 and rest of the age groups are close to each other. Also, the percentage of different race groups is also the same for all except White. The major difference between the two populations is the size of the population 2003-2008 Study has more than 10000 people in the study as compared to 1988-1993 Study.

2. We would obtain the information about whether the participant uses illicit drugs or not and summarize the data based on gender, age, and race. The reference group is the group of people who do not use illicit drugs and the exposure group will be the group of people who use illicit drugs.