The above Investigators sampled 10,725 adult participants (20-69 years) in the 1981 survey and a total of 593 deaths occurred during 13 years of follow up. The mortality status of the participants was determined by linking the survey database to the National Mortality Database. The mortality database contained all deaths records and is updated regularly from death registrations. The following table displays the number of deaths recorded (Canadian Fitness survey, Journal of Clinical Epidemiology 2001; 54:916-920). Subjects were placed in Body Mass Index (BMI) categories according to reported height and weight on the survey.
BMI Class
|
n
|
Follow up time (person years)
|
Deaths
|
Underweight
|
314
|
3,882
|
16
|
Normal weight
|
6,173
|
76,887
|
236
|
Overweight
|
4,238
|
51,746
|
341
|
I. Calculate the 13-year cumulative incidence for each weight category.
this estimates the risk that an individual will experience an event or develop adiseaseduring a specified period of time. the number of new events or cases of disease divided by the total number of individuals in the population at risk for a specific time interval.
II. Calculate the 13-year cumulative incidence ratio comparing the Underweight group (exposed group) to the Normal Weight group (non-exposed group).
III. Calculate the 13-year cumulative incidence ratio comparing the Overweight group (exposed group) to the Normal Weight group (non-exposed group).
IV. Calculate the incidence rate for each weight category.
V. Calculate the incidence rate ratio comparing the Underweight group (exposed group) to the Normal Weight group (non-exposed group).
VI. Calculate the incidence rate ratio comparing the Overweight group (exposed group) to the Normal Weight group (non-exposed group)
VII. If the 95% confidence interval of the risk ratio of rates of death among underweight and overweight versus normal weight were 0.93-2.85 and 1.39-6.29 respectively which one of this would you consider statistically significant? Explain your answer