24. A study conducted in Cape Coast recruited 200 pregnant women with either gestational diabetes (GDM) or gestational hypertension (GHPT) diagnosed at 20 weeks gestation and 800 pregnant women free from any disorder of pregnancy and followed them up until delivery to assess incidence of preterm birth (PTB) among this population of women. Twenty-one and half percent (21.5%) and 19.8% of the women with GDM/GHPT and with no pregnancy disorder were lost to follow up, respectively. The person-weeks of follow up among women with GDM/GHPT and with no pregnancy disorder was 3570 and 14420, respectively. The proportion of PTB recorded among women with GDM/GHPT and with no pregnancy disorder at the end of the study was 59.2% and 20.2%, respectively. a. Calculate the cumulative incidence of PTB in the population (2 marks) b. Calculate the incidence rate of PTB in the population (2 marks) c. Calculate the risk Yatio, incidence rate ratio, and attributable fraction for exposed women based on incidence.proportions. Interpret your results (6 marks) d. Calculate the odds of PTB among exposed and unexposed women (3 marks) e. Calculate the relative odds and compare with the risk ratio (3 marks) f. Can the relative odds computed be assumed to be a good approximation of the risk ratio? Briefly explain (2 marks) g. What is the main validity concern in this study? What is the cause of this validity issues?
