Bhaskaran, K;
Forbes, HJ;
Douglas, I;
Leon, DA;
Smeeth, L;
(2013)
Representativeness and optimal use of body mass index (BMI) in the UK Clinical Practice Research Datalink (CPRD).
BMJ Open
, 3
(9)
, Article e003389. 10.1136/bmjopen-2013-003389.
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Abstract
Objectives: To assess the completeness and representativeness of body mass index (BMI) data in the Clinical Practice Research Datalink (CPRD), and determine an optimal strategy for their use. Design: Descriptive study. Setting: Electronic healthcare records from primary care. Participants: A million patient random sample from the UK CPRD primary care database, aged ≥16 years. Primary and secondary outcome measures: BMI completeness in CPRD was evaluated by age, sex and calendar period. CPRD-based summary BMI statistics for each calendar year (2003–2010) were age-standardised and sex-standardised and compared with equivalent statistics from the Health Survey for England (HSE). Results: BMI completeness increased over calendar time from 37% in 1990–1994 to 77% in 2005–2011, was higher among females and increased with age. When BMI at specific time points was assigned based on the most recent record, calendar–year-specific mean BMI statistics underestimated equivalent HSE statistics by 0.75–1.1 kg/m2. Restriction to those with a recent (≤3 years) BMI resulted in mean BMI estimates closer to HSE (≤0.28 kg/m2 underestimation), but excluded up to 47% of patients. An alternative strategy of imputing up-to-date BMI based on modelled changes in BMI over time since the last available record also led to mean BMI estimates that were close to HSE (≤0.37 kg/m2 underestimation). Conclusions: Completeness of BMI in CPRD increased over time and varied by age and sex. At a given point in time, a large proportion of the most recent BMIs are unlikely to reflect current BMI; consequent BMI misclassification might be reduced by employing model-based imputation of current BMI.
| Type: | Article |
|---|---|
| Title: | Representativeness and optimal use of body mass index (BMI) in the UK Clinical Practice Research Datalink (CPRD) |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1136/bmjopen-2013-003389 |
| Publisher version: | http://dx.doi.org/10.1136/bmjopen-2013-003389 |
| Language: | English |
| Additional information: | This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/ |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1449658 |
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