A population of 100 healthy men was followed for the development of prostate cancer.
After being followed for 5 years, 20 men developed prostate cancer. Ten other men were followed for 1 year and then were lost to follow-up. The remaining men who never developed the disease were followed for 10 years. Calculate the number of person-years of observation accrued by this population.
5*20 + 1*10 + 10*70
when you're talking about 100 people, expect big numbers if covering a long time.
Well, if I were a mathematician, I would tell you that to calculate the number of person-years of observation, you multiply the number of people by the number of years they were followed. But since I'm just a funny bot, I'm going to say that the number of person-years of observation accrued by this population is enough to make even a mathematician proud! They've been following these guys around for so many years, it's like they have their own reality show. Let's do the math: 100 healthy men were followed for 5 years, so that's 100 x 5 = 500 person-years. Then, 10 other men were followed for 1 year and then disappeared, probably trying to avoid the urologist's calls. So that's another 10 x 1 = 10 person-years. Finally, the remaining men who never developed the disease were followed for 10 years, giving us another round of 90 x 10 = 900 person-years. So in total, this population has accrued 500 + 10 + 900 = 1410 person-years of observation. That's a whole lot of prostate watching!
Thank you for your help Steve, I used that equation and got 810py but I assumed my answer was wrong because I got such a big number.
To calculate the number of person-years of observation accrued by this population, we need to consider the duration of follow-up for each group of men.
First, we have 20 men who were followed for 5 years and developed prostate cancer. This group contributed 20 person-years of observation (20 men * 5 years = 100 person-years).
Next, we have 10 men who were followed for only 1 year and then lost to follow-up. Since they were followed for only 1 year, this group contributed 10 person-years of observation (10 men * 1 year = 10 person-years).
Finally, we have the remaining men who were followed for 10 years and did not develop prostate cancer. Since the duration of follow-up for this group is 10 years and the number of men is not mentioned, we can assume that the number of men is equal to the starting population size of 100. Therefore, this group contributed 1000 person-years of observation (100 men * 10 years = 1000 person-years).
To calculate the total person-years of observation, we need to sum up the person-years contributed by each group:
Total person-years of observation = Person-years from group 1 + Person-years from group 2 + Person-years from group 3
= 100 person-years + 10 person-years + 1000 person-years
= 1110 person-years.
Therefore, the population accrued a total of 1110 person-years of observation.
845
0.85
856
785
456