Subjective and Objective Methods of Assessing Walking Limitation Due to Claudication
Condition: Intermittent Claudication
MeSH terms: Intermittent Claudication
Study type: Observational

Summary: 
      Leg artery disease is a common condition in which fatty deposits develop in the blood vessels
      that supply the legs. Many patients with leg artery disease experience a cramp-like leg pain
      during walking that is relieved by rest; this is called intermittent claudication. To help
      determine the severity of leg artery disease, patients may be questioned about how far they
      can walk before claudication pain forces them to stop. However, this information is usually
      of limited use because most patients poorly estimate their walking capacity. The
      investigators have developed a simple questionnaire to help estimate walking capacity in
      patients with leg artery disease. The purpose of this study is to test the validity and
      reliability of this questionnaire. By validity, the investigators mean the extent to which
      the questionnaire measures what it is supposed to measure (walking capacity). By reliability,
      the investigators mean the extent to which the questionnaire produces the same results over
      time when completed on two different days.

      The investigators hypothesise that the investigators simple questionnaire will be valid and
      reliable.
    

Detailed description: 
      Claudication is a chronic condition that impairs walking capacity. Lower-extremity peripheral
      arterial disease (PAD) is a frequent cause of claudication. Claudication is suspected to be
      vascular-type (i.e. of arterial origin) when pain or discomfort occurs in the leg muscles
      during exercise and is relieved within 10 min of rest. The "maximal walking distance" (MWD;
      the distance at which pain forces the patient to stop walking) is of great importance for
      assessing the severity of claudication. Patient interview is the most readily accessible way
      of estimating walking capacity in routine clinical practice; however, patients with PAD
      typically poorly estimate their walking capacity. Open questions about the distance a patient
      can walk before limb pain or discomfort forces them to stop lack standardisation. Questions
      such as "Because of a health or physical problem, do you have any difficulty walking for one
      mile?" only allow for a yes/no response. The functional status component of the 86-item
      PAVK-86 questionnaire appears useful for estimating MWD, but this is a time-consuming tool.
      The Walking Impairment Questionnaire (WIQ), which was proposed over a decade ago to
      standardise the estimation of walking capacity by patient interview, is widely used. However,
      the WIQ is also relatively complex (14 items with 5 possible answers for each item: 70
      boxes), which often results in a large number of errors when self-completed by the patient.
      Furthermore, the WIQ score is difficult to obtain by mental calculation.

      The investigators have developed a simple, 4-item questionnaire, called the Estimation of
      Ambulation Capacity by History Questionnaire (EACH-Q), for estimating walking capacity in
      patients with symptomatic PAD (vascular-type claudication). The EACH-Q estimates the maximal
      duration that can be achieved (8 possibilities ranging impossible to 3 hours or more) at 4
      different displacement speeds (from slow walking to running). Scores can be obtained easily
      by multiplying the rank of each possible answer (impossible being zero) by a speed factor. We
      recently validated the EACH-Q against constant-load treadmill-walking-test performance in
      patients suffering from vascular-type claudication. However, further research is needed to
      assess the validity of the EACH-Q against other objective tests of walking capacity (e.g.
      incremental treadmill-walking test, 6-min walk test), and to assess its reproducibility.

      Hence, the aims of this study are: (i) to assess the validity of the EACH-Q against objective
      measures of walking capacity obtained from the Gardner-Skinner incremental treadmill-walking
      test and the 6-min walk test, and; (ii) to assess the inter-day reproducibility of the
      EACH-Q. The results will be compared against those obtained from the WIQ, and the participant
      cohort will be patients suffering from vascular-type claudication.
    

Observational model: Case-Only
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Patients with intermittent claudication recruited from hospital clinics
      
Keywords: walking impairment; claudication; treadmill; questionnaire