Objective: To describe the methodological challenges of a nine months follow up study of mothers recruited from a national Prevention of Mother To Child Transmission (PMTCT) programme with regards to defaulters, drop outs and compliance.
Design: Nested case control study.
Setting: Three peri-urban clinics in Zimbabwe namely: Epworth, St Mary's, Seke North.
Method: Pregnant women who enrolled at 36 weeks of gestation were recruited for a follow up of mother and child from delivery, six weeks, four and nine months post partum. Follow up trend of these women was compared between the HIV positive and negative mothers with regards to defaulting, drop outs, full and partial compliance. Statistical significance was computed using the Chi-square test.
Results: Of the enrolled 1050 pregnant women with a known HIV status (594 HIV negative and 456 HIV positive) 851 (457 HIV negative and 394 HIV positive) showed up at one or more visits scheduled up to nine months. The denominator was dropping at each point and time. The overall dropout rate was 19% without a significant difference between the HIV positive and negative women at delivery. At six weeks the drop out rate was 35 (7.7%) for the HIV positive versus 75 (12.9%) p=0.010 and at four months 12 (2.9%) versus 39 (7.7%) p=0.002 respectively. However, at nine months the drop out rate was not different (p=0.747). The defaulter rate was significantly different at every stage between the HIV positive and negative mothers from delivery to six weeks, becoming even more significant at the four and nine months visit (p=<0.001). The overall full compliance at nine months was 46.1% with a significant difference between the HIV positive (55.6%) versus (37.9%) for the HIV negative (p=<0.001).
Conclusion: Drop out is highest among the HIV negative as opposed to the HIV positive with the peak period being at "six weeks". There is high defaulting among the HIV negative compared to the HIV positive with the peak being at "four months". The study has shown that the HIV negative women are more likely to drop out whereas the HIV positive were twice as likely to fully comply. It is surprising that the peak drop out period, "six weeks visit" is a cardinal existing national scheduled visit where both mother and baby undergo a full medical examination with the mother having a pap smear taken.