Development of a multivariate model of the six-minute walked distance to predict functional exercise capacity in hypertension

Abstract

BackgroundHypertension is associated with deterioration of musculoskeletal function and functional capacity. Existing prediction models for assessment of the 6-min walk test (6MWT) do not capture the disease-related functional capacity. This study developed a multivariate prediction model of the measured 6-min walked distance (6MWDM) in hypertension and proposed target-values based on optimal therapeutic aims. MethodsSeventy-six patients (38 men, 56.1 ± 14.3 years, systolic pressure 156.7 ± 17.5 mmHg, diastolic pressure 92.9 ± 6.9 mmHg) underwent anamnesis, physical examination, and laboratory analysis. Functional capacity was assessed using the 6MWT, being the 6MWDM considered as the dependent variable. Independent variables included sex (S, coded ‘male’ = 1, ‘female’ = 0), age (A), body height (H), body mass, mean blood pressure (MBP), and physical activity (IPAQ, coded 1–5). Target-values were derived from theoretical scenarios of optimal blood pressure and physical activity, separately and combined. ResultsPatients walked 324.5 ± 10.1 m in the average of two trials 30-min apart. Pearson's correlation coefficient showed moderate-to-weak significant associations between 6MWDM and all independent variables. The final multivariate model was 6MWDP = 611.347–4.446 × MBP + 267.630 × H – 1.511 × A + IPAQcode + Scode (adjusted R2 = 0.680, SE of bias = 6.3 m), suggesting that clinical, anthropometric, and hemodynamic information determines functional capacity. Predicted values yielded a group-average of 325 ± 87 m. Target-values under the optimal scenario resulted in 420 ± 60 m. ConclusionsSex (men), higher body height, higher physical activity, lower mean blood pressure, and lower age are independently correlated with higher 6MWDM in patients with hypertension. Target-values can be estimated for therapeutic aims related to hemodynamics and lifestyle.