Chronic venous disorders and injection drug use: impact on balance, gait, and walk speed.

PURPOSE: Injection drug users are at high risk for chronic venous disorders (CVD), a condition resulting in a progressive deterioration of venous function of the legs. However, the effects of CVD on walking mobility in this population have not been studied. We examined a causal model of the relationship between injection drug use, CVD, and Walking Mobility. The validity of the Tinetti Balance and Gait scales and walk speed as a composite measure of Walking Mobility was also explored.

SETTING AND SUBJECTS: The participants were 104 men and women from a methadone maintenance treatment center. Drug use included 18 persons who injected drugs only in the hands, arms, and above the waist; 70 who injected all over the body including the lower extremities; and 16 who never injected drugs but used illegal substances by other routes. Forty-nine percent of participants had moderate to severe CVD.

DESIGN: Participants were classified into 2 groups according to their history of injection drug use: (a) those who injected in the lower extremities (n = 70) and (b) those who injected in the arms plus those who did not inject (n = 34). All measurements were obtained at baseline and again approximately 6.5 weeks later. Structural equation modeling was used to examine the causal effect of CVD on Walking Mobility. The validity of the Balance and Gait scales and the walk time variable as measures of a Walking Mobility factor was examined using a second-order confirmatory factor analysis.

INSTRUMENTS: Questionnaires included the Demographic and Health History and Drug History. The lower extremities were evaluated with the clinical portion of the Clinical-Etiology-Anatomy-Pathophysiology classification. Participants completed the Tinetti Balance and Gait test. A timed 6-m walk at the person's normal pace was used to calculate walk speed.

RESULTS: Test-retest reliability of the Tinetti Balance and Gait test and walk speed ranged from 0.79 to 0.86. Balance and gait scores were skewed toward the high end of the scale. Walking speed was slow. The leg-injecting group had lower Balance (P < .05) and Gait (P < .01) scores. A structural equation modeling showed that CVD was related to Walking Mobility after controlling for age, gender, body mass index, and comorbidities. Injection drug use and age were linked to Walking Mobility through CVD severity. Although fall information was not collected as part of our study, 15% of participants had a Tinetti score of less than 19, indicating a high risk for falls.

CONCLUSIONS: Tinetti Balance and Gait scales and walking speed are reliable and valid measures for the evaluation of walking mobility among persons with a history of drug use. Further research is needed to alleviate the impact of venous disease on walking mobility.