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Use of stance time variability for predicting mobility disability in community-dwelling older persons: a prospective study.
Tuesday,2012-11-06 12:26 America/Los_Angeles — eenright
| Title | Use of stance time variability for predicting mobility disability in community-dwelling older persons: a prospective study. |
| Publication Type | Journal Article |
| Year of Publication | 2012 |
| Authors | Brach, JS, Wert, D, VanSwearingen, JM, Newman, AB, Studenski, SA |
| Journal | J Geriatr Phys Ther |
| Volume | 35 |
| Issue | 3 |
| Pagination | 112-7 |
| Date Published | 2012 Jul-Sep |
| ISSN | 2152-0895 |
| Keywords | Aged, Aged, 80 and over, Disability Evaluation, Female, Gait, Geriatric Assessment, Humans, Independent Living, Male, Mobility Limitation, Physical Therapy Modalities, Postural Balance, Prospective Studies, Reproducibility of Results |
| Abstract | <p><b>BACKGROUND AND PURPOSE: </b>Mobility disability is a serious and frequent adverse health outcome associated with aging. Early identification of individuals at risk for mobility disability is important if interventions to prevent disability are to be instituted. The objectives of this prospective study were to (1) determine the magnitude of stance time variability (STV) that discriminates individuals who currently have mobility disability (prevalent mobility disability) and (2) determine the magnitude of STV that predicts a new onset of mobility disability at 1 year (incident mobility disability).</p><p><b>METHODS: </b>A total of 552 community-dwelling older adults were evaluated as part of the Cardiovascular Health Study, a longitudinal cohort study. Stance time, in milliseconds, was determined from 2 passes on a 4-m computerized walkway at self-selected walking speed, and STV was defined as the standard deviation from approximately 12 individual steps. Mobility disability was defined as self-reported difficulty walking a one-half mile. Receiver operating characteristic (ROC) curves were plotted to determine an optimal cutoff value for STV for prevalent and incident mobility disability, and the area under the receiver operating characteristic curve (AUC) was computed.</p><p><b>RESULTS: </b>The optimal cutoff score for STV (maximizing sensitivity and specificity) for prevalent mobility disability was 0.037 seconds (sensitivity = 65%, specificity = 65%, AUC = 0.70) and for incident 1-year mobility disability was 0.034 seconds (sensitivity = 61%, specificity = 60%, AUC = 0.65). The use of likelihood ratios demonstrated a gradient of risk across values of STV, with mobility risk increasing as values of STV increased.</p><p><b>DISCUSSION AND CONCLUSION: </b>Values of STV may be useful in identifying older adults with mobility disability and at risk for future disability. We recommend the more conservative estimate for identifying risk, STV = 0.034 seconds, which maximizes the sensitivity and minimizes false negatives. The relatively modest values on the validity indices could possibly be improved by increasing the reliability of the measurement of STV. Clinicians should interpret the cutoff values liberally and use STV in conjunction with other measures until further work is completed to validate STV as an indicator of mobility disability.</p> |
| DOI | 10.1519/JPT.0b013e318243e5f9 |
| Alternate Journal | J Geriatr Phys Ther |
| PubMed ID | 22314273 |
| PubMed Central ID | PMC3349774 |
| Grant List | K23 AG026766-01 / AG / NIA NIH HHS / United States P30 AG024827 / AG / NIA NIH HHS / United States N01 HC085081 / HC / NHLBI NIH HHS / United States U01 HL080295 / HL / NHLBI NIH HHS / United States N01 HC075150 / HC / NHLBI NIH HHS / United States N01-HC-85081 / HC / NHLBI NIH HHS / United States P30 AG024827-09 / AG / NIA NIH HHS / United States N01 HC015103 / HC / NHLBI NIH HHS / United States N01 HC085083 / HC / NHLBI NIH HHS / United States 1 P30 AG024827-01 / AG / NIA NIH HHS / United States N01 HC085085 / HC / NHLBI NIH HHS / United States TG 32AG00181 / AG / NIA NIH HHS / United States N01HC55222 / HL / NHLBI NIH HHS / United States T32 AG000181-22 / AG / NIA NIH HHS / United States N01-HC-85086 / HC / NHLBI NIH HHS / United States N01HC85086 / HL / NHLBI NIH HHS / United States N01 HC085082 / HC / NHLBI NIH HHS / United States N01-HC-85082 / HC / NHLBI NIH HHS / United States N01 HC085080 / HC / NHLBI NIH HHS / United States N01 HC-55222 / HC / NHLBI NIH HHS / United States K23 AG026766 / AG / NIA NIH HHS / United States 1 K23 AG026766-01 / AG / NIA NIH HHS / United States T32 AG000181 / AG / NIA NIH HHS / United States N01 HC055222 / HC / NHLBI NIH HHS / United States N01-HC-85083 / HC / NHLBI NIH HHS / United States N01-HC-75150 / HC / NHLBI NIH HHS / United States N01-HC-85080 / HC / NHLBI NIH HHS / United States N01 HC085084 / HC / NHLBI NIH HHS / United States N01HC75150 / HL / NHLBI NIH HHS / United States N01-HC-85079 / HC / NHLBI NIH HHS / United States N01HC85079 / HL / NHLBI NIH HHS / United States N01 HC085079 / HC / NHLBI NIH HHS / United States R01 AG023629 / AG / NIA NIH HHS / United States N01 HC045133 / HC / NHLBI NIH HHS / United States N01 HC035129 / HC / NHLBI NIH HHS / United States |