Person- Length of follow up - Outcome 3 years - lost- to follow up 7 years - end

Question

Person- Length of follow up- Outcome

3 years- lost- to follow up

7 years- end of the study

4 years to CHD DX; 7 years total follow up- DX with CHD; still alive at the end of study

5 years- to CHD DX; 6 years total follow up- DX with CHD; dies from CHD one year later

2 years- DX with CHD in ER; dies in the ER from CHD

6 years- lost to follow up

7 years- end of the study

7 years- end of the study; develops CHD one year later

The following are hypothetical data from a (small) cohort study with person-time denominators. Each person was followed for seven years unless indicated other-wise. The outcome of interest is coronary heart disease (CHD). DX means diagnosed. Using these data, calculate following: 1. CHD IR (incidence rate) 2. CHD MR (mortality rate)

Explanation / Answer

Totally there are 45 person years. In the study period, three persons have developed the disease and there is only one death during the study period.

1) The incidence rate of CHD is given by the formula,

= (Number of new cases)/(total person-time of observation)

= (3/45)

= 0.067 per person-year

= 6.7 per 100 person years

2) Mortality rate = (number of deaths)/(total number of person-time of observation)

= 1/45

= 0.022 per person-year

= 2.2 per 100 person-year

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.