Kelly A Shaw
It is recommended that healthcare providers1–5 routinely assess their patients’ physical activity (PA). However, there is limited evidence to guide general practitioners in their choice of assessment method. Currently, it is suggested that GPs assess PA from patient self report.6 Previous research by the authors has shown that self report by history taking was the method of choice for Australian GPs.7 While using self report is acceptable to GPs, it has limitations,8 including the risk of overreporting (social desirability bias) and patients finding it difficult to translate their activities into the appropriate intensity grade.7 An alternative to history taking is the use of questionnaires, but these also rely on self report, and even in the research setting such instruments vary in their effectiveness8 when compared against objective measures of physical activity such as pedometers or accelerometers.
It is unclear what is the best method of
accurately identifying physically inactive
patients in general practice. This study
aimed to compare the performance of
different methods of assessing patient
physical activity levels in general practice.
Thirteen general practitioners were
randomly allocated to perform either their
usual assessment, or this with a Lifescripts
tool, on consecutive patients. The authors
measured patients’ physical activity by
accelerometer over 1 week, including
steps per day, then calculated agreement,
kappa specificity, sensitivity, positive and
negative predictive value (PV) and ROC
characteristics for each assessment
method (GPs’ usual assessment, Lifescripts
tool and steps per day) against the
reference standard of accelerometer
Data from 29 patients was included.
Agreement between subjective
assessments was highest for GPs’ usual
assessment (agreement 73%; kappa
0.47; p=0.03), which also gave the
highest area under the ROC curve (0.75,
95% CI: 0.52–0.98). However, this still
had low specificity (67%) and positive PV
(63%). Using a cut-off of 7500 steps/day
maximised the area under the ROC curve
at 0.91 (95% CI: 0.82–1.00), 19.2% greater
than GPs’ usual assessment.
Measuring steps per day may be a
feasible and more effective way to screen
for physically inactive patients than self
report. A large scale study to confirm these
results is necessary.
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