Participants and procedure
The study was approved by the Scientific and Research Ethics Committee of the Medical Research Council, Semmelweis University (ETT TUKEB 285/2015) and was carried out in accordance with the tenets of the Declaration of Helsinki. Data collection took place between November 2015 and February 2018, with participants recruited from the practices of 33 general practitioners from across Hungary.
PAD usually appears after the age of 50 years, with an exponential increase after the age of 65 years. According to governmental regulations of the country of study, it is obligatory to record every patients’ ankle-brachial index (ABI) values every two years after reaching the age of 45; therefore, the target population included men and women aged 45 or older with at least one major vascular risk factor (current smoking, type 2 diabetes, or hypertension). Altogether, 300 (Mage = 65.3 years, SD = 8.7 years; 61.0% female) individuals agreed to participate in the present study. Patients provided written informed consent.
Participants’ medical history and the presence of major cardiovascular risk factors were recorded based on the health records kept by their general practitioners. The in-person examination started by completing the Edinburgh Claudication Questionnaire, a validated and frequently used method of screening for intermittent claudication. The Questionnaire has a sensitivity of over 80-90% and a specificity of over 95% (9). Second, the basic body measurements (height and weight) were performed. After a 5-minute rest, blood pressure and pulse were measured on both upper extremities (using a blood pressure manometer, Bosch Konstante) three times. Following current recommendations for the calculation of the ankle-brachial index (ABI) (1), systolic pressure on all four extremities was also measured with a continuous wave Doppler-US instrument at 8 MHz (multiDOPPY).
Based on at-rest ABI values and symptoms, four patient-groups were determined. Patients with negative at-rest ABI results without any symptoms indicating sclerosis were considered as ‘clear PAD-negative’. Patients with normal at-rest ABI values but whose Edinburgh Questionnaire results revealed symptoms of intermittent claudication (e.g., pain following walking uphill or climbing stairs) were coded as ‘ABI-negative-symptomatic’. The ‘clear PAD-positive’ group comprised patients whose ABI results were positive and clearly suffered from atherosclerosis, asymptomatic or symptomatic stenosis or occlusion reducing the blood flow. Patients, whose major arteries are hardened for various reasons (such as medial sclerosis), have non-compressible arteries. Due to this, blood pressure values at the ankle often show false high values; the Doppler Index is over 1.4. This subgroup of participants was labelled as the ‘non-compressible-artery group’.
Depressive symptoms were measured with the shortened Hungarian version of the Beck Depression Inventory (BDI), which is a 9-item questionnaire to assess depression severity (10). Each item is scored on a 4-point scale ranging from 0 (not at all characteristic of me) to 3 (very characteristic of me). Internal consistency of the scale proved to be excellent in the current sample (Cronbach’s α = .86). To allow international comparability, the total score of the 9-item version was transformed to its equivalent in the 21-item original version by multiplying the total scores by 2.22. The cut off score indicating the presence of at least mild depression was therefore identical to that in the international literature (≥10).
Personality dimensions (extraversion, agreeableness, conscientiousness, neuroticism and openness) were measured with the Big Five Inventory (BFI-44) (11). On the 44-item questionnaire, each item is rated on a 5-point scale ranging from 1 (strongly disagree) to 5 (strongly agree). Internal consistency of the dimensions was good in the current sample (Cronbach’s α-s of .89, .75, .71, .84, and .90, respectively).
The Kolmogorov-Smirnov test indicated that the distribution of all continuous variables differed significantly from the normal distribution. Therefore, when investigating the relationship between peripheral arterial disease status and these variables, the non-parametric Kruskal-Wallis test was used. When examining the association between the dependent variable and the categorical independent variables, the chi square test was employed. On the multivariate level, a multinomial logistic regression analysis was conducted to investigate the role of all independent variables in differentiating between those intact from peripheral arterial disease (‘clear PAD-negative’) versus those affected (‘ABI-negative-symptomatic’, ‘non-compressible-artery’ and ‘clear PAD-positive’).