225pple were followedup for 10yrs to determine the incident rate of developing HIV. At 5yrs of followup. 20 cases of HIV were detected, & the end of the study 30 cases were detected. What' the IR of?

To calculate the incidence rate (IR) of developing HIV over the 10-year follow-up period, we need to divide the number of new cases of HIV by the total person-years at risk.

Total person-years at risk = 225 people x 10 years = 2250 person-years

Number of new cases of HIV = 30 cases - 20 cases = 10 cases

Incidence rate (IR) = Number of new cases of HIV / Total person-years at risk
Incidence rate (IR) = 10 cases / 2250 person-years
Incidence rate (IR) = 0.0044 cases per person-year

Therefore, the incidence rate of developing HIV over the 10-year follow-up period is 0.0044 cases per person-year.

The incidence rate (IR) is the number of new cases of a disease that develop in a specific population over a specific period of time. In this case, the IR is the number of new cases of HIV that developed in the population of 225 people over the 10-year follow-up period.

To calculate the IR, we need to divide the number of new cases by the total person-years of follow-up. The total person-years of follow-up is the sum of the number of years that each person was followed up. In this case, the total person-years of follow-up is 225 people - 10 years = 2,250 person-years.

The number of new cases of HIV is 30. Therefore, the IR is 30 / 2,250 = 0.0133 cases per person-year. This means that the average rate of developing HIV in this population was 1.33% per year.