Advanced PH2710 Epidemiologic Methods I Levels of analysis Ecologic studies discussion
Fall 2001 In class: 11/19/01
Reference Bongaarts J, Reining P, Way P, Conant F. The relationship between male circumcision and HIV infection in African populations. AIDS 1989;3:373-7. Discussion questions 1. Identify the causal hypothesis motivating the research. 2. Identify the target (population and etiologic time period). 3. Identify a causal contrast corresponding to the study question, specifying the appropriate disease frequency measure for the contrast. 4. Identify the study population and size. 5. Identify the exposure and outcome variable(s) and in whom they are measured. 6. Identify the unit of analysis. 7. Identify the substitute(s) for the causal contrast employed by the investigators. 8. Did the investigators use the best available substitute(s)? If not, how would you have improved the design? 9. What might explain the observed association other than a cause-effect relationship? a. The following text appears in the introduction of the paper by Bongaart et al.
We document here strong a statistical correlation between national estimates of male circumcision and HIV seroprevalence in the capitals of 37 African countries. This continent-wide result is consistent with that of a case-control study in a Nairobi clinic which found that uncircumcised men were significantly more likely to be infected with HIV than circumcised controls. The absence of male circumcision may therefore be a crucial factor in the spread of HIV in Africa.
What type of bias in interpretation might this represent? b. The authors cautioned that while they found a strong population level correlation between male circumcision and HIV seroprevalence, thei...