Thanks, got a good idea about the 2 types of measures of incidence and how their denominators differ. But I am not able to wrap my brain around the extension part....
I am struggling with this question. Please Help me!!!! Suppose that you are funded to engage in a study of chronic obstructive pulmonary disease (COPD) in a fixed population of 1,500 people. The study lasts for three years (January 1, 2012 - December 31, 2014). At the beginning of the study (January 1, 2012), 11 people are identified as already having COPD. Six additional people develop COPD during 2012, and two of those six people with COPD died (these six people are at risk for a total of four person-years during 2012); five additional people develop COPD in 2013, and two of those people with COPD died (these five people are also at risk for a total of nine person-years); seven additional people develop COPD in 2014, and two of these people with COPD died ( these seven people are at risk for a total of 19 person-years during 2013). Assume that deaths during the "current" year are ignored in the denominator of incidence and period prevalence rates. a) What is the point prevalence rate (per 1,000) of COPD on January 1, 2012? (2 marks) b) What is the point prevalence rate (per 1,000) of COPD on January 1, 2013? (2 marks) c) What is the period prevalence rate (per 1,000) of COPD during 2013? (2 marks) d) What is the incidence rate (per 1,000) of COPD for 2012? (2 marks) e) What is the incidence rate (per 1,000) of COPD for 2014? (2 marks) f) What is the incidence density (per 1,000 persons-years) of COPD for the entire three years? (2 marks)
Hello i am a little confused you said you was counting the number of new cases within the time frame you only counted 3 when their were actually 4 people who developed cancer within the 10 year time frame
you said at 5:56 that "they are at risk any time that they Dont have cancer AND they are alive. But you're also counting the years of the people after they developed cancer (until they died). So you're basically counting every year that someone is alive. Could you or someone clarify, im a bit confused.
Hi Dr. Rahul..I have a concern about this calculation! Could I pls know why you added the years after when they got the disease when it comes to calculate the person years? As an example in patient 1 he exposed and got disease within one year.. so he met risk from one year.. so isn't he have 1 person year?
Dear Dr. Rabul. Many thanks about this video. But I wonder why are you counting the years before the people get into the study as a part of people - time to calculating Incidence rate? This video help me a lot. Thank youuu.
Thank you for your wonderful and clarity presentation. Could you please help me to clarify my puzzles? 1) what is different between "cumulative incidence" and "incidence rate"? are they the same? because I know that incidence are divided into two types, cumulative incidence and incidence density, but the way Epidemiologists use to calculate make me very confusingly. Some exercises use population at risk at the beginning of study as a denominator, but some use population at mid-time period as denominator. so which way is correct? Thanks a lot!
According to the follow up they are different...I mean when you follow 100% whole it means cumulative but when you follow and you miss some of them it means incidence rate of density okaay
If the first and 9th person had 8 and 3 person years, respectively, shouldn't it follow that the 6th person should have 8 year person time. And if 5th and 7th person's have 9 and 8 year person time then 4th and11th person should have 7 and 8 person years. Please help me understand when to stop the count going by your examples
2 things 1- shouldn't u exclude people once they get the disease? Wether they die or not once they develop it they are not at risk bc they are already diseased 2- I still don't understand how the sum of the years that ppl spend in risk can reflect the population at risk during the whole period, even when u try to interrupt it it doesn't make sense
Hey rahul, why are you counting the years between getting cancer and dying as part of the person-time? once a person gets cancer shouldn't they no longer be considered "at risk" of getting it since they already have it? thanks!
I also noticed those who had cancer did not join at the very beginning of the study although the years they contributed are calculated as such. An example is the person who died of cancer after the study ended how comes she/he also contributed their time in the first years while he/she joined at year six?
@@nanc-x4p Look at the definition of incidence once again, it says in the denominator "people at risk". So in a given time frame though the person might have developed cancer at suppose 6th year, but he was at risk since year 1. That's why we count initial years as well.
You are called to investigate a possible health problem in an office building that may be due to a potential environmental toxin. You arrange with a company that occupies two levels of the building to follow all 300 office employees for 30 days. Every day the employees report their health status. Nothing happens until day 10, when 35 employees report of respiratory distress. On day 20, 70 employees report of respiratory distress. The remaining employees do not report any problems over the 30 day period. What is the incidence rate of respiratory distress in this study population? a. 1.4 per 100 persondays b. 2.1 per 100 persondays c. 2.8 per 100 persondays d. 1.0 per 100 persondays Can anyone solve this for me??
Hello Rahul, Thank you for the video but I won’t like to ask a question, The first person at risk did not start the study but you counted the first year of person risk. Can you clarify that please Thank you
You compounded everything may be cos I've not been following why not one example of new cases of one condition in a population then represent it in the formula I think it would be more clearer
He did it based off people who died of cancer, not new cases of cancer. Had he done it based off new cases of cancer then he would have included that patient in the numerator.
how did sir know that the person was going to die nd not include him and since he's calculating incidence(burden) nd not specific death rate he must have made it into 4nd not 3
Aswanaa Sathyasai He was looking at the incidence of people that died due to the disease in a 10 year period. Once he died out the time period time period, he cannot be included. If the study continued for another 10 years, then number 4 will be added in the numerator.
Please recheck the 3rd person, counting from the top entered the study at the 6th year and got to the 10th year. So the contribution is 4years not 10yrs
If the first and 9th person had 8 and 3 person years, respectively, shouldn't it follow that the 6th person should have 8 year person time. And if 5th and 7th person's have 9 and 8 year person time then 4th and11th person should have 7 and 8 person years. Please help me understand when to stop the count going by your examples
I think there is 4 new case and not 3 could you explain it?
I was thinking about it too
I think so as well
Great video. Rahul, I liked the way you break it down. THANK YOU!!!
Thanks, got a good idea about the 2 types of measures of incidence and how their denominators differ. But I am not able to wrap my brain around the extension part....
Thank you so much for your time doing this video! it is helping mea lot!
👍👍 I learn statistics well with your teaching 👍👍
What if some subjects disaper for a while and then come back? Are they included in the denominato?
God bless you...you gave me a concept to hang to
Thanks dr for clarify this subject , but i wanna to ask why its 3 new cases not four ..
I am struggling with this question. Please Help me!!!!
Suppose that you are funded to engage in a study of chronic obstructive pulmonary disease (COPD) in a fixed population of 1,500 people. The study lasts for three years (January 1, 2012 - December 31, 2014). At the beginning of the study (January 1, 2012), 11 people are identified as already having COPD. Six additional people develop COPD during 2012, and two of those six people with COPD died (these six people are at risk for a total of four person-years during 2012); five additional people develop COPD in 2013, and two of those people with COPD died (these five people are also at risk for a total of nine person-years); seven additional people develop COPD in 2014, and two of these people with COPD died ( these seven people are at risk for a total of 19 person-years during 2013).
Assume that deaths during the "current" year are ignored in the denominator of incidence and period prevalence rates.
a) What is the point prevalence rate (per 1,000) of COPD on January 1, 2012? (2 marks)
b) What is the point prevalence rate (per 1,000) of COPD on January 1, 2013? (2 marks)
c) What is the period prevalence rate (per 1,000) of COPD during 2013? (2 marks)
d) What is the incidence rate (per 1,000) of COPD for 2012? (2 marks)
e) What is the incidence rate (per 1,000) of COPD for 2014? (2 marks)
f) What is the incidence density (per 1,000 persons-years) of COPD for the entire three years? (2 marks)
How did the 3rd person acquire 10 person time yet he was not their in the beginning
it was very interesting and quite explaination. I do want to ask you how can it be calculated maternal death?
It helps me a lot T_T Thank you very much for spend your time making this video
Hello i am a little confused you said you was counting the number of new cases within the time frame you only counted 3 when their were actually 4 people who developed cancer within the 10 year time frame
He's calculating new cases of death from cancer and not new cases of cancer.
Christylove71 did he say that ?
@@drholiday4147 yes
how do you calculate prevalence and overall prevalence without duration. when prevalence is equals to incidence x duration
I count 88 person-years. Regardless of the number, my question is how do I change it to months?
Why did you count people who joined late in study as 10 years.
Thanks a lot, Rahul ,its helpful, but it needs to be repeated to get good through my brain
you said at 5:56 that "they are at risk any time that they Dont have cancer AND they are alive. But you're also counting the years of the people after they developed cancer (until they died). So you're basically counting every year that someone is alive. Could you or someone clarify, im a bit confused.
My epidemiology instructor says that the month of death is not counted in the person years. I guess this is debatable?
Hi Dr. Rahul..I have a concern about this calculation! Could I pls know why you added the years after when they got the disease when it comes to calculate the person years? As an example in patient 1 he exposed and got disease within one year.. so he met risk from one year.. so isn't he have 1 person year?
Inverse of icidence rate gives survival time??
Why a third person excluded from new cases?
Very summarized and smartly
Thank you you made it very clear and easy
Dear Dr. Rabul. Many thanks about this video. But I wonder why are you counting the years before the people get into the study as a part of people - time to calculating Incidence rate?
This video help me a lot. Thank youuu.
Exactly my question
why we does not consider 3rd person as new case
Thank you for your wonderful and clarity presentation. Could you please help me to clarify my puzzles? 1) what is different between "cumulative incidence" and "incidence rate"? are they the same? because I know that incidence are divided into two types, cumulative incidence and incidence density, but the way Epidemiologists use to calculate make me very confusingly. Some exercises use population at risk at the beginning of study as a denominator, but some use population at mid-time period as denominator. so which way is correct? Thanks a lot!
According to the follow up they are different...I mean when you follow 100% whole it means cumulative but when you follow and you miss some of them it means incidence rate of density okaay
Cumulative incidence is the incidence proportion. While incidence rate is taken per person time.
If the first and 9th person had 8 and 3 person years, respectively, shouldn't it follow that the 6th person should have 8 year person time.
And if 5th and 7th person's have 9 and 8 year person time then 4th and11th person should have 7 and 8 person years.
Please help me understand when to stop the count going by your examples
2 things
1- shouldn't u exclude people once they get the disease? Wether they die or not once they develop it they are not at risk bc they are already diseased
2- I still don't understand how the sum of the years that ppl spend in risk can reflect the population at risk during the whole period, even when u try to interrupt it it doesn't make sense
Is it like saying that every 100 years about 4 people would develop the disease ?
Hey rahul,
why are you counting the years between getting cancer and dying as part of the person-time? once a person gets cancer shouldn't they no longer be considered "at risk" of getting it since they already have it? thanks!
+Mohammed Kamareddine - If I'm understanding correctly, we are measuring the incidence of DEATH rate, not the incidence of cancer rate.
Thank you so much !!! ❤❤
isn't the number of person years according to your explanation supposed to 88 person years? am confused
It's one missed number, just assume the total is 80.
I also noticed those who had cancer did not join at the very beginning of the study although the years they contributed are calculated as such. An example is the person who died of cancer after the study ended how comes she/he also contributed their time in the first years while he/she joined at year six?
@@nanc-x4p Look at the definition of incidence once again, it says in the denominator "people at risk". So in a given time frame though the person might have developed cancer at suppose 6th year, but he was at risk since year 1. That's why we count initial years as well.
That is impressive thanks
You are called to investigate a possible health problem in an office building that may be due to a potential environmental toxin. You arrange with a company that occupies two levels of the building to follow all 300 office employees for 30 days. Every day the employees report their health status. Nothing happens until day 10, when 35 employees report of respiratory distress. On day 20, 70 employees report of respiratory distress. The remaining employees do not report any problems over the 30 day period. What is the incidence rate of respiratory distress in this study population? a. 1.4 per 100 persondays b. 2.1 per 100 persondays c. 2.8 per 100 persondays d. 1.0 per 100 persondays
Can anyone solve this for me??
Hello Rahul,
Thank you for the video but I won’t like to ask a question,
The first person at risk did not start the study but you counted the first year of person risk.
Can you clarify that please
Thank you
The totol is 88 he made a mistake 😭 I think so plz reply sir 🙏🙏🙏
Well explained.
You compounded everything may be cos I've not been following why not one example of new cases of one condition in a population then represent it in the formula I think it would be more clearer
Summing the person years I had 88.. 🤔🤔 but sir wrote 80 person years....I'm a bit confuse...anyone to help me out please?
88 is correct actually
In your explanation the person is counted as being at risk... all the way up to the and counting the month that they are gone.
there is 4 number of new cases but u wrote 3. how??
He did it based off people who died of cancer, not new cases of cancer. Had he done it based off new cases of cancer then he would have included that patient in the numerator.
mixable15 it's within the time period. One person died after the time period so it's nnot included. Hope that makes sense?
how did sir know that the person was going to die nd not include him and since he's calculating incidence(burden) nd not specific death rate he must have made it into 4nd not 3
Aswanaa Sathyasai He was looking at the incidence of people that died due to the disease in a 10 year period. Once he died out the time period time period, he cannot be included. If the study continued for another 10 years, then number 4 will be added in the numerator.
💯
Please recheck the 3rd person, counting from the top entered the study at the 6th year and got to the 10th year. So the contribution is 4years not 10yrs
Why 3 new cases and not 4?
Why only person who dies is counted, as oppose to those developed disease during this time?
when i added the denominator, i had 88, but you added, you reached 80
same
how new cases are 3 and not 4?
Well Explained
Why add times for people who wasn’t In the study in year 1, 2, 3....etc?
I’m confused too.
thank you sir
thank you so much but the sum of person years is 88 not 80 !!!!
Poor soul died from heartbreak 😂
Hi Mr Rahul I'm requesting ur email
If the first and 9th person had 8 and 3 person years, respectively, shouldn't it follow that the 6th person should have 8 year person time.
And if 5th and 7th person's have 9 and 8 year person time then 4th and11th person should have 7 and 8 person years.
Please help me understand when to stop the count going by your examples