I am looking for understanding better the variables COPD and asthma in the SHHS.
1/ On COPD for say the first visit there is:
variable "copd15": Doctor of Medicine (MD) said participant had chronic obstructive pulmonary disease (COPD)?
variable "crbron15": Doctor of Medicine (MD) said participant had chronic bronchitis?
variable "emphys15": Doctor of Medicine (MD) said participant had emphysema?
It is my understanding that emphysema or chronic bronchitis are two types of COPD, yet the COPD variable has only n=62 positive test when emphysema has n=132 and chronic bronchitis has n=315. How is it possible?
There are two potentially interesting variables for asthma. My interest is to know if the patient has asthma at the time of the PSG whether SHHS1 or SHHS2. For that purpose I wonder which of these two variables might be the best proxy?
hi201e: e. Do you still have asthma?
asthma15: Doctor of Medicine (MD) said participant had asthma?
3/ On both COPD and asthma
How much time spam between the CPOD/asthma examination and the PSG recording? Is it in the order of days, months, years?
For "asthma15" is it the answer to a questionnaire filled just before SHHS2?
4/ Diagnosis modality
How were COPD and asthma diagnosed? Is it documented somewhere?
What does it mean "Doctor of Medicine (MD) said participant had chronic obstructive pulmonary disease (COPD)?"? Does it relates to a specific test made for diagnosing COPD by the doctor who then reports COPD for the patient?
Everything from the Health Interview is self-report. There was no confirmation, diagnostic testing, nor medical chart review done to compare with what the participant marked on the questionnaire.
#1 - I'm guessing "COPD" is a term less people had discussed with their doctors. SHHS1 was almost 25 years ago now so I'm not sure how these pulmonary diseases were conceptualized and presented to patients back then.
#2 - I think you'll want "asthma15"/"asth1215" for SHHS1 and "hi201d"/"hi201e" for SHHS2. In SHHS1 we only know if they ever received a diagnosis and whether they had an asthma attack in the last 12 months (asth1215), which you might use as a proxy for "having asthma at the time of the PSG".
#3 - The Health Interview questionnaires should have been done around the time of the actual PSGs in the SHHS visits. So, I expect it's on the order of days. (Comparing "stdatep" and "formdate_hi" could be informative; at a glance they look to match as I expect.)
#4 - Unfortunately all we have is self-report. I expect the parent cohorts have more definitive information about testing, diagnoses, and ongoing presence/treatment.
Thanks Mike, I will go with #2 as of now.