Question

PPH4801/MPHDHM9 JAN/FEB 2017 SECTION B. You MUST answer a TOTAL of THREE (3) questons QUESTION 1 An investigator wants to assess whether smoking is a nsk factor for pancreatic cancer Electronic medical records at a local hospital will be used to identfy 50 patents with pancreatic cancer One hundred patients who are similar but free from pancreatic cancer will also be selected Each particapant's health record will be analysed for smoking history 11 Name the type of study proposed 12 Indicate the proposed study s strengths and weaknesses 13 What is the most likely source of bias in this proposed study? (12) (12) 125) QUESTION 2 In a cohort study in Johannesburg infant feeding practices and the nsk of infant HIV infection at 3 months of age were assessed A total of 941 HIV infected mothers and their infants (HIV negative) were enrolled These mother-infant pairs were divided into exposure groups with respect to feeding practices, including exclusive breastfeeding (ne91) and mixed feeding (n 355) groups By three months of age, eleven of the exclusıvely breastfed babies and 77 of the moxed feeding babies had developed HIV nfection 21 Construct a two dimensional contingency table (2x2) of the above data? 22 Calculate the incidence of outcome (HIV status) in the two groups, mixed feedıng and exclusive breast feeding. and compare the outcomes Please offer an explanation or interpretation of your result owing are baby heght measurements (in centimetres) for a sample of s participating in a study of infant health Construct a frequency distnbution nfant more Height in cm 28 30 41 48 29 ble using the data and the following categones less than 35, 35-44, 45-54, 55 or 48 62 49 51 39 (10) (25) ITURN OVER

Answer 1

Answer-1.1-this is a type of cohort study, as we are going to study prospectively about risk factors.

Answer1. 2 strength of the cohort study- chances of recall bias are very less.

Provides incidence, relative risk.

Allows study of several etiological factors simultaneously.

Only exposure, has occurred. outcomes has not occured

Weakness of cohort study-ethical problems are there.

Lost to follow up.

Time consuming.

Expensive.

Not suitable to investigate rare diseases.

Answer1. 3-selection bias can be there when we are selecting cohorts.

Hawthorne bias-patient changes his behavior during follow up.

Analyzer and interviewer bias can be there.