Question

97 Extra Problem The graph below shows the follow-up period on 7 individuals for 5 years in order to study the association between an exposure (smoking) and a disease (lung cancer) #1 Non Exposed 42 Exposed #3 Exposed *4 Non Exposed #5 Nou Exposed *6 Exposed # 7 Non Exposed Did mot develop my disease Developed the disease Withdrew from the staty Was lost to follow-up Developed another disease Developed the disease at 4.5 years Developed the disense Stady Year (a) What is the type of this study? (b) Calculate the total person-time for all the individuals. (c) Calculate the total person-time among: - Exposed • Not Exposed. (d) Fill in the table below. Disease No disease Total PY Exposed Not Exposed (e) Calculate the EER, CER and the Risk Ratio (RR). Interpret. (1) Calculate the incidence density for both groups (Exposed and Not Exposed). (g) Deduce the Rate Ratio. Interpret. (h) In this study, which of the following measures is more appropriate: the Risk Ratio or the Rate Ratio? Justify your answer.

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Answer 1

This study is survival analysis. Total Pesson ting: - Complete (Not Exposed) - yeah 2nd Lеам. Exposed 3 year old Exposed 4 year. Non Exposed Ѕ рол, Мәм 2 три 4.5 years Exposed, 1 2 year Nou Exposed, Tortaal 1 24.3 year) co Exposed = 1 + 3+4.5 = 8.5 years Not exposed I 24.5-8.5 = 16 years. Disease No obsean py 1 Care is d) Exposed 2 I to of another Not disease which we cannot consider for diseade because reason is different No of Pesson disen (C EER= Exposed. = 2 2 2 = 0.67 Nă of Person déseaus CER = Not Exposed. -- = 0.25 RR = Go incidene in Exposed incidenc in unexposed There is Risk Ratio suggest that the the persons are in Exposed group (smoking) has 2.67 times more disk to develop a buy cancer disease. Exposed e 22.67

23 per looo year (f) Incideme density) - ID=no' of new Cases - Person time at risk for Exposed groups 2% = 0.235=2-3 % ID for Un Exposed goong = 1/16 = 0.063 = -6% (9) Rate Ratio = 0.235 = 3173 Person who smoke had 3.73 times the rate of - dung cancer. to person who had not smoke (b) In my opinion. Rate Ratio is better than Risk Ration in suwival analysis study because it includes the Home of person tha. 6 per 1000 year - 0.063