Does smoking history change depending on the way questions are asked?

Abstract

Smoking history is crucial to identify patients at risk for several diseases, influences therapeutic decisions and study eligibility. Some smokers however appear uncertain about answering when inquiries are made in order to obtain the number of pack-years (PY) smoked.

Aim: To investigate whether a different number of PY is reported depending on the way inquiries about smoking history are made.

Methods: We compared two different kinds of investigating questions regarding smoking history in smokers visiting the respiratory outpatient clinic.

First, inquiries typeA (non-specific) were made in all subjects:"For how many years have you smoked and how many cigarettes a day did you smoke on average?"

Then, inquiries typeB (specific) were made:"At what age did you start and at what age did you quit smoking?" Subsequently, subjects’ answers were linked to specific events in their lives (e.g. "Did you start to smoke when you were a student/ in the army/etc.? Did you quit smoking at retirement/ pregnancy, ect.)"Did you smoke 20 cigarettes a day on average?" The answer to the latter question was further explored depending on the observation of patients’ body language.

Results: Eighty smokers (66% male, average age 67(+11)y) participated in the study. Answers to non-specific questions(A) were perceived as more vague and answers to specific questions(B) as more accurate by the investigator. The reported PY based on inquiries type A (40(±28)) was significantly lower than PY reported based on inquiries type B (51(±30)) (p=0.023).(t-Test)

Conclusion: The way of inquiring about smoking history may significantly alter the number of reported pack-years, with more specific questions resulting in higher, but probably more realistic numbers.