Smoker, ex-smoker or non-smoker? The validity of routinely recorded smoking status in UK primary care: a cross-sectional study
Open accessAbstract
Objective: To investigate how smoking status is recorded in UK primary care; to evaluate whether appropriate multiple imputation (MI) of smoking status yields results consistent with health surveys. Setting: UK primary care and a population survey conducted in the community. Participants: We identified 354 204 patients aged 16 or over in The Health Improvement Network (THIN) primary care database registered with their general practice 2008–2009 and 15 102 individuals aged 16 or over in the Health Survey for England (HSE). Outcome measures: Age-standardised and age-specific proportions of smokers, ex-smokers and non-smokers in THIN and the HSE before and after MI. Using information on time since quitting in the HSE, we estimated when ex-smokers are typically recorded as non-smokers in primary care records. Results: In THIN, smoking status was recorded for 84% of patients within 1 year of registration. Of these, 28% were smokers (21% in the HSE). After MI of missing smoking data, the proportion of smokers was 25% (missing at random) and 20% (missing not at random). With increasing age, more were identified as ex-smokers in the HSE than THIN. It appears that those who quit before age 30 were less likely to be recorded as an ex-smoker in primary care than people who quit later. Conclusions: Smoking status was relatively well recorded in primary care. Misclassification of ex-smokers as non-smokers is likely to occur in those quitting smoking at an early age and/or a long time ago. Those with no smoking status information are more likely to be ex-smokers or non-smokers than smokers.
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- Authors
- Marston, L., Carpenter, J. R., Walters, K. R., Morris, R. W., Nazareth, I., White, I. R., & Petersen, I.
- Affiliations
- University College London (GB)
- London School of Hygiene & Tropical Medicine (GB)
- University of Cambridge (GB)
- Corresponding author
- Marston, Louise
- ORCID
- Venue
- BMJ Open
- Publisher
- BMJ
- Published
- 2014-04
- Volume
- 4
- Issue
- 4
- Pages
- e004958
- ISSN
- 2044-6055 (ISSN-L)
- PMC
- PMC4010810
- OpenAlex
- W2147730333
- Cited by
- 105
- References
- 37
- Citations by year
- 2026: 10 · 2025: 9 · 2024: 11 · 2023: 5 · 2022: 4 · 2021: 12 · 2020: 16 · 2019: 13 · 2018: 12 · 2017: 3 · 2016: 4 · 2015: 5 · 2014: 1
- FWCI
- 2.89
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- cc-by
- Locations
- BMJ Open (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Bristol Research (University of Bristol) (publishedVersion)
- LSHTM Research Online (London School of Hygiene and Tropical Medicine) (acceptedVersion)
- UCL Discovery (University College London) (submittedVersion)
- HighWire Press Open Archive (submittedVersion)
- Funders
- Medical Research Council (G0900701)
- Topics
- Health Sciences › Medicine › Physiology › Smoking Behavior and Cessation
- Health Sciences › Health Professions › Health Information Management › Medical Coding and Health Information
- Social Sciences › Sociology and Political Science › Survey Methodology and Nonresponse
- Keywords
- smoking status, former smokers, primary care records, data quality, multiple imputation, missing data, misclassification, time since quitting, Health Improvement Network, Health Survey for England, smoking prevalence
- MeSH terms
- Adult, Age Factors, Aged, Aged, 80 and over, Cross-Sectional Studies, England, Female, Health Surveys, Humans, Male, Middle Aged, Primary Health Care, Smoking, Smoking Cessation, Young Adult, Electronic Health Records
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