Association between the ankle–brachial index, intermittent claudication, and physical activity level: what is the influence on the functional capacity of patients with or at high risk of cardiovascular disease?

Figures & data

Table 1 Characteristics of the study sample

Baseline characteristics	Normal ABI (n=104)	Borderline PAD (n=23)	PAD (n=35)	Total (n=162)	P-value*
Male sex, n (%)	65 (62.5)	14 (60.9)	25 (71.4)	104 (64.2)	0.595
Age (years), mean ± SD	63.4±6.6	66.4±8.8	68.4±7.6	64.9±7.4	0.002a
Caucasian ethnicity, n (%)	93 (89.4)	20 (87.0)	33 (94.3)	146 (90.1)	0.153
BMI (kg/m^2), mean ± SD	27.6±3.9	27.9±5.3	26.9±4.1	27.5±4.1	0.617
Outcome variables
IC, n (%)	9 (8.7)	1 (4.3)	32 (91.4)	42 (25.9)	<0.001b,a
ABI (mmHg), mean ± SD	1.11±0.06	0.94±0.02	0.83±0.07	1.03±0.13	<0.001a,b,c
6MWD (meters), mean ± SD	349.3±71.6	298.1±77.3	330.0±75.6	338.0±75.0	0.009c
6MWD (percent of predicted), mean ± SD	76.0±14.5	67.6±14.4	76.1±16.3	74.8±15.1	0.046c
IPAQ (score), mean ± SD	660.2±448.3	880.4±716.3	670.0±551.7	693.6±518.4	0.175
Eligibility criteria
CAD, n (%)	82 (78.8)	20 (87.0)	28 (80.0)	130 (80.2)	0.676
CVD, n (%)	15 (14.4)	6 (26.1)	5 (14.3)	26 (16.0)	0.367
Diabetes, n (%)	25 (24.0)	2 (8.7)	10 (28.6)	37 (22.8)	0.187
Metabolic syndrome, n (%)	73 (70.2)	14 (60.9)	28 (80.0)	115 (71.1)	0.279
Smoking, n (%)	20 (19.2)	3 (13.0)	5 (14.3)	28 (17.3)	0.675
HTN, n (%)	97 (93.3)	21 (91.3)	33 (94.3)	151 (93.2)	0.906
Age >70 years, n (%)	19 (18.3)	9 (39.1)	16 (45.7)	44 (27.2)	0.003a,c
Dyslipidemia, n (%)	53 (51.0)	12 (52.2)	12 (34.3)	77 (46.5)	0.207
Asymptomatic carotid disease, n (%)	2 (1.9)	1 (4.3)	1 (2.9)	4 (2.5)	0.784
Family history of CAD, n (%)	40 (38.5)	3 (13.0)	13 (37.1)	56 (34.6)	0.064
CKD, n (%)	6 (5.8)	0 (0.0)	0 (0.0)	6 (3.7)	0.176
Medication use
Statin, n (%)	74 (71.2)	19 (82.6)	23 (65.7)	116 (71.6)	0.372
Acetylsalicylic acid, n (%)	62 (59.6)	18 (78.3)	23 (65.7)	103 (63.6)	0.233
Beta-blockers, n (%)	64 (61.5)	16 (69.6)	21 (60.0)	101 (62.3)	0.733
ACEI, n (%)	80 (76.9)	12 (52.2)	23 (65.7)	115 (71.0)	0.045c
ARB, n (%)	7 (6.7)	3 (13.0)	3 (8.6)	13 (8.0)	0.596
Calcium channel blockers, n (%)	16 (15.4)	2 (8.7)	5 (14.3)	23 (14.2)	0.707
Oral anticoagulants, n (%)	30 (28.8)	6 (26.1)	7 (20.0)	43 (26.5)	0.590

Notes:

* Comparison between ABI values (normal, borderline, and PAD).

a Difference between normal and PAD;

b difference between borderline and PAD;

c difference between normal and borderline.

Abbreviations: 6MWD, 6-minute walk distance; ABI, ankle–brachial index; ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin II receptor blocker; BMI, body mass index; CAD, coronary artery disease; CKD, chronic kidney disease; CVD, cardiovascular diseases; HTN, hypertension; IC, intermittent claudication; IPAQ, International Physical Activity Questionnaire; PAD, peripheral artery disease.

Table 2 Pearson’s correlation coefficients (r) and confidence intervals between outcome variables and absolute distance walked in the 6MWT

Variable	r	95% CI	P-value
Age (years)	−0.347	−0.47 to −0.17	<0.001
IPAQ (score)	0.164	0.23–0.30	0.038
ABI	0.216	0.07–0.34	0.006
IC (0= yes, 1= no)	0.785	0.67–0.89	<0.001

Abbreviations: 6MWT, 6-minute walk test; ABI, ankle–brachial index; CI, confidence interval; IC, intermittent claudication; IPAQ, International Physical Activity Questionnaire.

Table 3 Multiple linear regression analysis with distance walked in 6MWT as the dependent variable

Variable	Coefficient B	95% CI	P-value
Constant	419.214	221.3–617.1	<0.001
Age (years)	−2.788	−4.34 to −1.23	0.001
ABI	131.386	26.2–236.49	0.001
IC (0= yes, 1= no)	34.737	3.50–65.96	0.029

Note: R²_adjusted=0.147.

Abbreviations: 6MWT, 6-minute walk test; ABI, ankle–brachial index; CI, confidence interval; IC, intermittent claudication.