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Using a single question to assess physical activity in older adults: a reliability and validity study.

Gill DP, Jones GR, Zou G, Speechley M - BMC Med Res Methodol (2012)

Bottom Line: Discriminant validity was similar for both questions.For the relative physical activity question, there was moderate agreement when this question was re-administered seven days later, fair to moderate/good associations when compared with indicators of physical function, and little to no associations when compared with measures hypothesized to be theoretically not related to physical activity.The relative physical activity question had the best combination of test-retest reliability, convergent validity and discriminant validity.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Alzheimer's Coordinating Center, Department of Epidemiology, University of Washington, Seattle, WA, USA. dpgill2@uw.edu

ABSTRACT

Background: Single-item physical activity questions provide a quick approximation of physical activity levels. While recall questionnaires provide a more detailed picture of an individual's level of physical activity, single-item questions may be more appropriate in certain situations. The aim of this study was to evaluate two single-item physical activity questions (one absolute question and one relative question) for test-retest reliability, convergent validity, and discriminant validity, in a sample of older adults.

Methods: Data was obtained from the Project to Prevent Falls in Veterans, a fall risk-factor screening and modification trial. One question measured absolute physical activity (seldom, moderately, vigorously active) and one measured relative physical activity (more, about as, less active than peers). Test-retest reliability was examined using weighted Kappa statistics (κ) in a sample of 43 subjects. Validity was assessed using correlation coefficients (r) in participants who received clinical assessments (n = 159).

Results: The absolute physical activity question was more reliable than the relative physical activity question (κ = 0.75 vs. κ = 0.56). Convergent validity, however, was stronger for the relative physical activity question (r = 0.28 to 0.57 vs. r = 0.10 to 0.33). Discriminant validity was similar for both questions. For the relative physical activity question, there was moderate agreement when this question was re-administered seven days later, fair to moderate/good associations when compared with indicators of physical function, and little to no associations when compared with measures hypothesized to be theoretically not related to physical activity.

Conclusions: The relative physical activity question had the best combination of test-retest reliability, convergent validity and discriminant validity. In studies requiring a measure of physical activity, where physical activity is not the primary focus and more detailed measures are not feasible, a single question may be an acceptable alternative.

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Formation of validity sample from the Project to Prevent Falls in Veterans. The dashed line indicates the point in the larger study where measures of interest for the present study begin. a Clinical assessments were not required to be part of the larger study. b Validation measures used in the present study were taken from CA2. c CA2 and telephone interviews were completed as close together in time as possible. The median number of days was 37 days for all participants (n = 159) and 33 days for the subset who also had VCA data (n = 94). Abbreviations: CA1 = first clinical assessment; interRAI = interRAI Community Health Assessment (earlier version); VCA = Veterans' Comprehensive Assessment; CA2 = second clinical assessment.
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Figure 1: Formation of validity sample from the Project to Prevent Falls in Veterans. The dashed line indicates the point in the larger study where measures of interest for the present study begin. a Clinical assessments were not required to be part of the larger study. b Validation measures used in the present study were taken from CA2. c CA2 and telephone interviews were completed as close together in time as possible. The median number of days was 37 days for all participants (n = 159) and 33 days for the subset who also had VCA data (n = 94). Abbreviations: CA1 = first clinical assessment; interRAI = interRAI Community Health Assessment (earlier version); VCA = Veterans' Comprehensive Assessment; CA2 = second clinical assessment.

Mentions: For the validity sample, the mean age was 80 (SD 3.9) years, and close to two-thirds were males. Other characteristics of participants included in the validity sample are presented in Table 1. About 20% self-reported fair or poor health, 38% reported one or more falls in the past 12 months, 49% reported that their memory was worse than five years ago, 15% reported being seldom active and 12% reported that they were less active compared to their peers. In comparison to women, men were older (mean age 81 years, SD 3.5), and a slightly higher percentage reported fair or poor health, one or more falls in the past month and worse memory compared to five years earlier. Men and women provided similar responses in regard to their PA compared to their peers. The median time between administration of validation measures and PA questions ranged between 33 days for the subset of participants who had been administered both the earlier version of the interRAI Community Health Assessment (interRAI) and Veterans' Comprehensive Assessment (VCA), and 37 days when considering all participants in the validation sample (also see Figure 1).


Using a single question to assess physical activity in older adults: a reliability and validity study.

Gill DP, Jones GR, Zou G, Speechley M - BMC Med Res Methodol (2012)

Formation of validity sample from the Project to Prevent Falls in Veterans. The dashed line indicates the point in the larger study where measures of interest for the present study begin. a Clinical assessments were not required to be part of the larger study. b Validation measures used in the present study were taken from CA2. c CA2 and telephone interviews were completed as close together in time as possible. The median number of days was 37 days for all participants (n = 159) and 33 days for the subset who also had VCA data (n = 94). Abbreviations: CA1 = first clinical assessment; interRAI = interRAI Community Health Assessment (earlier version); VCA = Veterans' Comprehensive Assessment; CA2 = second clinical assessment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3313867&req=5

Figure 1: Formation of validity sample from the Project to Prevent Falls in Veterans. The dashed line indicates the point in the larger study where measures of interest for the present study begin. a Clinical assessments were not required to be part of the larger study. b Validation measures used in the present study were taken from CA2. c CA2 and telephone interviews were completed as close together in time as possible. The median number of days was 37 days for all participants (n = 159) and 33 days for the subset who also had VCA data (n = 94). Abbreviations: CA1 = first clinical assessment; interRAI = interRAI Community Health Assessment (earlier version); VCA = Veterans' Comprehensive Assessment; CA2 = second clinical assessment.
Mentions: For the validity sample, the mean age was 80 (SD 3.9) years, and close to two-thirds were males. Other characteristics of participants included in the validity sample are presented in Table 1. About 20% self-reported fair or poor health, 38% reported one or more falls in the past 12 months, 49% reported that their memory was worse than five years ago, 15% reported being seldom active and 12% reported that they were less active compared to their peers. In comparison to women, men were older (mean age 81 years, SD 3.5), and a slightly higher percentage reported fair or poor health, one or more falls in the past month and worse memory compared to five years earlier. Men and women provided similar responses in regard to their PA compared to their peers. The median time between administration of validation measures and PA questions ranged between 33 days for the subset of participants who had been administered both the earlier version of the interRAI Community Health Assessment (interRAI) and Veterans' Comprehensive Assessment (VCA), and 37 days when considering all participants in the validation sample (also see Figure 1).

Bottom Line: Discriminant validity was similar for both questions.For the relative physical activity question, there was moderate agreement when this question was re-administered seven days later, fair to moderate/good associations when compared with indicators of physical function, and little to no associations when compared with measures hypothesized to be theoretically not related to physical activity.The relative physical activity question had the best combination of test-retest reliability, convergent validity and discriminant validity.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Alzheimer's Coordinating Center, Department of Epidemiology, University of Washington, Seattle, WA, USA. dpgill2@uw.edu

ABSTRACT

Background: Single-item physical activity questions provide a quick approximation of physical activity levels. While recall questionnaires provide a more detailed picture of an individual's level of physical activity, single-item questions may be more appropriate in certain situations. The aim of this study was to evaluate two single-item physical activity questions (one absolute question and one relative question) for test-retest reliability, convergent validity, and discriminant validity, in a sample of older adults.

Methods: Data was obtained from the Project to Prevent Falls in Veterans, a fall risk-factor screening and modification trial. One question measured absolute physical activity (seldom, moderately, vigorously active) and one measured relative physical activity (more, about as, less active than peers). Test-retest reliability was examined using weighted Kappa statistics (κ) in a sample of 43 subjects. Validity was assessed using correlation coefficients (r) in participants who received clinical assessments (n = 159).

Results: The absolute physical activity question was more reliable than the relative physical activity question (κ = 0.75 vs. κ = 0.56). Convergent validity, however, was stronger for the relative physical activity question (r = 0.28 to 0.57 vs. r = 0.10 to 0.33). Discriminant validity was similar for both questions. For the relative physical activity question, there was moderate agreement when this question was re-administered seven days later, fair to moderate/good associations when compared with indicators of physical function, and little to no associations when compared with measures hypothesized to be theoretically not related to physical activity.

Conclusions: The relative physical activity question had the best combination of test-retest reliability, convergent validity and discriminant validity. In studies requiring a measure of physical activity, where physical activity is not the primary focus and more detailed measures are not feasible, a single question may be an acceptable alternative.

Show MeSH
Related in: MedlinePlus