Cross-cultural validity of the Pulmonary Embolism Quality of Life questionnaire in the quality of life survey after pulmonary embolism: A Persian-speaking cohort

Abstract

Background: The Pulmonary Embolism Quality of Life (PEmb-QoL) questionnaire is the first disease-specific scale for assessing the quality of life in patients with a history of pulmonary embolism (PE).

Objectives: To assess the cross-cultural validity and reliability of the disease-specific PEmb-QoL questionnaire.

Methods: The Persian version was prepared through the forward and backward translation of the English questionnaire. Six months after the diagnosis of acute PE, consecutive Persian-speaking patients were asked to complete the PEmb-QoL, the generic 36-item Short Form (SF-36) questionnaires and undertake a 6-minute walk test (6MWT). Acceptability was assessed via item missing rate, reproducibility by the test-retest method, and internal consistency reliability by Cronbach's α and McDonald's ω coefficients. Convergence validity was assessed using the Spearman rank correlation between scores of PEmb-QoL, SF-36, and 6MWT. The questionnaire structure was evaluated through exploratory factor analysis.

Results: Ninety-six patients with a confirmed diagnosis of PE completed the questionnaires. The Persian version of PEmb-QoL had good internal consistency (α = 0.95, 3-factor ω = 0.96), inter-item correlation (0.3-0.62), item-total correlation (0.38-0.71), reproducibility (test-retest ICC with 25 participants = 0.92-0.99), and good discriminant validity. Convergence validity was confirmed by the moderate-to-high correlations between PEmb-QoL and SF-36 scores, and a good correlation between the "limitation in daily activities" dimension of the PEmb-QoL questionnaire and 6MWT results. Exploratory factor analysis suggested a 3-component structure with functional (items 1h, 4b-5d, 6, 8, 9i, and 9j), symptoms (1b-h, 7, and 8), and emotional (5a, 6, and 9a-h) components.

Conclusion: The Persian version of the PEmb-QoL questionnaire is valid and reliable for measuring the disease-specific quality of life in patients with PE.

Keywords: patient-reported outcome measures; psychometrics; pulmonary embolism; quality of life; reproducibility of results; surveys and questionnaires.

Graphical abstract

Figure 1

Flow diagram of exclusion criteria. PEmb-QoL, Pulmonary Embolism Quality of Life questionnaire; RHC, Rajaie Cardiovascular Medical and Research Center; SF-36, 36-item Short Form Health Survey.

Figure 2

Score distribution of the PEmb-QoL total scale and subscales. Individual scores are jittered along the horizontal axis to allow visual distinction. Floor or ceiling effects <15% are desirable. Less than 25% of items should have negative skewness, and less than 25% should have a skewness outside of -1 to 1 range. ∗ Patients with the lowest possible score, ie, the best quality of life for the corresponding dimension. † Patients with the highest possible score, ie, worst quality of life for the corresponding dimension. ADL, activities of daily living; FC, frequency of complaints; PEmb-QoL, Pulmonary Embolism Quality of Life questionnaire.

Figure 3

Convergent and discriminant validity (top) and domain intercorrelation (bottom) of the PEmb-QoL questionnaire. A moderate-to-high correlation between the theoretically similar dimensions is desired. PEmb-QoL, Pulmonary Embolism Quality of Life questionnaire; SF-36, 36-Item Short Form Health Survey.

Figure 4

Exploratory factor analysis (EFA) of the Persian version of the PEmb-QoL questionnaire with Oblimin rotation method. EFA uses a covariance matrix to extract a set of latent common variables that best explain the observed variance in the responses to questionnaire items. The 3 extracted factors accounted for 34%, 15%, and 11% of the total variance in patient responses. Factor loadings represent the regression coefficient of each item. Coefficients <0.35 were not mentioned. IC, intensity of complaint; PEmb-QoL, Pulmonary Embolism Quality of Life questionnaire; SL, social limitations.