This is a methodological study designed to assess the reliability and validity of the HAP questionnaire when administered via telephone to patients with CVD. The study followed the Consensus-Based Standards for the Selection of Health Measurement Instruments guidelines [18], which recommend a minimum of 50 participants for studies assessing measurement properties such as reliability and construct validity. This sample size is considered adequate to detect moderate to high intraclass correlation coefficients (ICCs; ICC >0.70) with sufficient statistical power in validation studies.

The study was approved by the institutional research ethics committee (number 5.456.711) and was conducted in accordance with the ethical standards outlined in the Declaration of Helsinki. All participants provided written informed consent before inclusion in the study.

Participants were recruited from a cardiovascular rehabilitation program, and the sample was composed of patients diagnosed with CVD. A convenience sampling method was used on the basis of availability and eligibility of patients enrolled in the program during the study period.

The inclusion criteria were individuals of both sexes who were aged between 50 and 90 years and with a confirmed diagnosis of CVD. The exclusion criteria included patients with auditory or cognitive impairments that could interfere with communication during the telephone interview and those who failed to complete the second part of the questionnaire within the maximum interval of 14 days between assessments.

A total of 56 participants met the eligibility criteria and completed both the face-to-face and telephone assessments. Demographic, clinical, and pharmacological characteristics of the sample are presented in Table 1.

The HAP questionnaire is composed of 94 items that assess an individual’s level of physical function across domains such as self-care, work, social engagement, and physical activity. The items are ordered by increasing metabolic demand, with higher item numbers representing activities that require greater energy expenditure [9,11].

Participants were asked to classify each activity as one they are “still doing,” have “stopped doing,” or have “never done.” The HAP questionnaire can be applied to individuals with a wide range of functional capacities—from very low (eg, getting in and out of bed without assistance) to very high (eg, running 4.8 kilometers) [9,11].

The questionnaire generates 2 primary scores:

The AAS is considered a more stable estimate of the individual’s typical functional level compared to the MAS, as it adjusts for discontinued activities. According to established cutoffs, AAS values categorize individuals as: inactive (AAS<53), moderately active (AAS=53‐74), and active (AAS>74) [9,14].

The HAP questionnaire was administered to each participant on 2 separate occasions: once in person and once via telephone. The interval between the two assessments ranged from 3 to 14 days (mean 8, SD 4.5 d), which was deemed appropriate to minimize recall bias while avoiding significant changes in clinical status [19].

Each participant completed both modes of administration only once, and both applications were conducted by the same trained physiotherapist who followed a standardized protocol to ensure consistency in tone, pacing, and instructions across both modalities.

The order of administration was not randomized, with all participants first completing the face-to-face assessment followed by the telephone interview. This fixed order was chosen to maximize adherence and reduce the risk of dropout, particularly among older participants, based on preliminary feasibility observations during pilot testing.

Categorical variables were reported as absolute frequencies and percentages, whereas continuous variables were expressed as means and SDs. To evaluate convergent validity, the mean differences (MDs) between face-to-face and telephone assessments were calculated along with 95% CIs.

Cronbach α was used to assess internal consistency, with values greater than 0.70 considered acceptable. The ICC was applied to determine test-retest reliability and temporal stability of the HAP questionnaire across administration modes. The magnitude of ICC was classified as follows: very high (>0.90), high (0.70‐0.89), moderate (0.50‐0.69), low (0.26‐0.49), and very low (<0.25) [19].

To assess agreement between the two methods, the Bland-Altman method was used, comparing the mean values and the differences between in-person and telephone assessments for MAS and AAS. The upper and lower limits of agreement were calculated as MD −1.96 to +1.96 times the SD of the differences, and plotted to visualize the dispersion and potential bias.

All statistical analyses were performed using R software (version 1.0), and a significance level of 5% (P<.05) was adopted.

This study demonstrated that the HAP questionnaire administered by telephone yields results highly consistent with those obtained through face-to-face application in patients with CVD. Both MASs and AASs showed no notable differences between modalities, and the instrument exhibited excellent internal consistency (Cronbach α=0.919), strong test-retest reliability (ICC=0.794 for MAS; ICC=0.910 for AAS), and acceptable agreement on Bland-Altman analysis with no systematic bias. These findings indicate that telephone administration is a valid, reliable, and practical alternative for assessing functional capacity in this population, supporting the feasibility of remote functional evaluation [10,11,13,14].

Building upon these findings, the HAP questionnaire offers additional advantages that reinforce its applicability in clinical and research settings. The questionnaire allows for quick and meaningful measurements of activity level changes, comparisons with healthy populations, and identification of activity patterns associated with medical conditions [11]. It has shown correlations with objective measures of cardiorespiratory fitness [20] and has been validated for use in various populations, such as individuals with chronic pain and knee osteoarthritis [21].

In this study, the questionnaire demonstrated good internal consistency, with a Cronbach α of 0.919, and strong reproducibility and temporal stability measured by the ICC, with MAS ICC=0.794 and AAS ICC=0.910. These findings align with previous validation studies. For example, a systematic review reported high consistency for MAS (0.76‐0.97) and AAS (0.79‐0.97), reinforcing the questionnaire’s measurement reliability [13].

The Cronbach α of 0.919 in this study is considered excellent and indicative of near-perfect reliability [22]. Similar values have been observed in previous research; one study reported a Cronbach α of 0.91 when applying the HAP questionnaire via interview in a community-dwelling older adult population [9], and another study found a Cronbach α of 0.93 in hospitalized patients [14], reinforcing the questionnaire’s internal consistency across diverse populations.

The internal consistency and temporal stability did not substantially differ between face-to-face and telephone administrations, suggesting that both methods are equally reliable. Our in-person results are consistent with previous studies; one investigation reported MAS and AAS of 71.6 and 63.6, respectively, in patients undergoing coronary artery bypass grafting [11], whereas another study observed an MAS of 79.76 and an AAS of 65.81 in patients with heart failure [10]. Importantly, this study is, to our knowledge, the first to evaluate both the internal consistency and the agreement of HAP questionnaire scores when administered in person versus by telephone.

The Bland-Altman analysis confirmed good agreement between administration methods. For MAS, the limits of agreement (95% CI) ranged from −19.3 to 12.1, and from −17.6 to 13.4 for AAS. These findings suggest that the differences between the modes are within acceptable limits, with no significant measurement bias introduced by the telephone modality. No previous studies have reported such agreement data for the HAP questionnaire using this method of comparison.

Several previous studies have successfully used telephone-based instruments in patients with CVD [15,16] and in poststroke populations [17,23]. For instance, one study assessed pharmacist-led telephone-based education and self-management support during the COVID-19 pandemic lockdown [15,23]. Another investigation examined angina prevalence among stable outpatients with CVD using remote methods [16], and a separate validation study confirmed the reliability of the Duke Activity Status Index administration by telephone in stroke survivors [17]. Telephone administration allows for faster, more direct data collection and extends access to individuals who may be unable to attend face-to-face assessments. To our knowledge, this is the first study to validate the use of the HAP questionnaire via telephone in patients with CVD.

The assessment of physical activity levels is a key component of both in-person and home-based exercise programs. Validating a tool like the HAP questionnaire for telephone administration broadens access to functional capacity assessment, particularly for individuals living in rural or remote areas, those with limited mobility, or patients who are unable to attend in-person sessions. This approach also facilitates multicenter research by enabling efficient and cost-effective data collection across geographically diverse populations. Additionally, traditional functional tests often require specialized equipment or trained professionals, representing a high financial burden and logistical barrier, particularly for underserved populations [24-27].

However, this study has some limitations. Certain patients may face challenges related to hearing loss, language comprehension, or cognitive deficits, which can interfere with telephone-based assessment. Moreover, the lower technological literacy commonly observed among older adults, combined with socioeconomic and ethnic disparities, may further limit the widespread applicability of telephone-based tools [28].

The results of this study demonstrated that the HAP questionnaire, when administered by telephone, shows adequate reliability, agreement, and internal consistency, supporting its use as a valid alternative for assessing physical activity levels in patients with CVD. These findings suggest that telephone-based administration of the HAP questionnaire may be a practical, accessible, and cost-effective tool for functional assessment in clinical and research contexts, especially when in-person evaluations are not feasible.