title: Walking impairment questionnaire improves mortality risk prediction models in a high-risk cohort independent of peripheral arterial disease status.
abstract: BACKGROUND
  The Walking Impairment Questionnaire (WIQ) is a subjective measure of patient-reported walking performance developed for peripheral arterial disease. The purpose of this study is to examine whether this simple tool can improve the predictive capacity of established risk models and whether the WIQ can be used in patients without peripheral arterial disease.
  
  
  RESULTS
  At baseline we assessed the walking distance, stair-climbing, and walking speed WIQ category scores among individuals who were undergoing coronary angiography. During a median follow-up of 5.0 years, there were 172 mortalities among 1417 study participants. Adjusted Cox proportional hazards models showed that all 3 WIQ categories independently predicted future all-cause and cardiovascular mortality, including among individuals without peripheral arterial disease (P<0.001). Compared with the cardiovascular risk factors model, we observed significantly increased risk discrimination with a C-index of 0.741 (change in C-index, 0.040; 95% confidence interval, 0.011-0.068) and 0.832 (change in C-index, 0.080; 95% confidence interval, 0.034-0.126) for all-cause and cardiovascular mortality, respectively. Examination of risk reclassification using the net reclassification improvement index showed a 48.4% (P<0.001) improvement for all-cause mortality and a 77.4% (P<0.001) improvement for cardiovascular mortality compared with the cardiovascular risk factors model.
  
  
  CONCLUSIONS
  All 3 WIQ categories independently predicted future all-cause and cardiovascular mortality. Importantly, we found that this subjective measure of walking ability could be extended to patients without peripheral arterial disease. The addition of the WIQ scores to established cardiovascular risk models significantly improved risk discrimination and reclassification, suggesting broad clinical use for this simple, inexpensive test.
authors: Division of Cardiovascular Medicine and Division of Vascular Surgery, Stanford University School of Medicine, Stanford, CA, USA. ktnead@stanford.edu
authors: Kevin T
authors: KT
authors: Nead
authors: Margaret
authors: M
authors: Zhou
authors: Roxanne
authors: R
authors: Diaz Caceres
authors: Jeffrey W
authors: JW
authors: Olin
authors: John P
authors: JP
authors: Cooke
authors: Nicholas J
authors: NJ
authors: Leeper
mesh_terms: D000368:Aged; D002140:California / Q000453:epidemiology; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology; D004185:Disability Evaluation; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009518:New York / Q000453:epidemiology; D058729:Peripheral Arterial Disease / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D016138:Walking
keywords: high-risk populations; mortality; peripheral artery disease; risk factors
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