The Severe Respiratory Insufficiency (SRI) Questionnaire A specific measure of health-related quality of life in patients receiving home mechanical ventilation

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Abstract

Background and Objective: The objective of this study was to develop a specific instrument for measuring health-related quality of life (HRQL) in patients receiving home mechanical ventilation (HMV).

Methods: The Severe Respiratory Insufficiency (SRI) Questionnaire was developed and tested for its psychometric properties following a multicentric clinical trial including 226 patients receiving HMV (mean age 57.3±14.0 years).

Results: Forty-nine items passed the selection process and were allocated to seven subscales: Respiratory Complaints, Physical Functioning, Attendant Symptoms and Sleep, Social Relationships, Anxiety, Psychologic Well-Being, and Social Functioning. Cronbach's α was >0.7 in all subscales and >0.8 in four subscales indicating high internal consistency reliability. Construct validity was confirmed by factor analysis, indicating one summary scale that accounts for 59.8% of the variance. Concurrent validity was confirmed by correlating subscales of the SRI and the SF-36 (0.21<r<0.79). Item-scale correlations revealed a high item discriminant validity. In addition, different diagnostic groups could be discriminated by the SRI. Here, the overall best HRQL was measured in the following order: patients with kyphoscoliosis, miscellaneous disorders, neuromuscular diseases, post-tuberculosis, and chronic obstructive pulmonary disease (P<.05).

Conclusion: The SRI is a new multidimensional instrument with high psychometric properties designed to measure specific HRQL in patients with SRI receiving HMV.

Introduction

During the last 2 decades evaluation of health-related quality of life (HRQL) has become steadily more essential in health care practice and research to evaluate the human and financial costs and benefits of modern medical techniques [1], [2], [3]. The definition of HRQL is based on different components of health including physical state, psychologic well-being, social relations, and functional capacities that are influenced by a persons experience, beliefs, expectations, and perceptions [1], [4], [5]. For the purpose of assessment of HRQL several instruments have been developed [2]. Generic instruments, such as the Sickness Impact Profile [6], the Nottingham Health Profile [7], and the MOS 36-Item Short-Form Health Survey (SF-36) [8], are not specific to any particular disease, and are therefore most commonly used for general survey research on health allowing comparisons between disease states. In contrast, disease-specific questionnaires such as the Chronic Respiratory Disease Questionnaire (CRQ) [9] and the St. George's Respiratory Questionnaire (SgrQ) [10] well-validated for patients suffering from chronic obstructive pulmonary disease (COPD) are necessary to focus on domains most relevant to a particular disease [1].

Home mechanical ventilation (HMV), delivered noninvasively by a facial mask, is a well-established treatment for hypercapnic chronic respiratory failure due to chest wall deformities, neuromuscular diseases, and COPD [11], [12]. Patients receiving HMV usually have severe chronic respiratory insufficiency with a past medical history of several years or decades, and suffer from end-stage disease with objectively severe limitations of daily living. In addition, HMV is a time-consuming and cost-intensive therapy. Therefore, several studies have been conducted in the last decade to evaluate HRQL in patients receiving HMV, most of them using nonspecific or COPD-specific questionnaires [13], [14], [15], [16], [17], [18]. However, several specific conditions that are important for the daily life of patients receiving HMV have not been addressed to questionnaires currently used for HRQL assessment in that study group. This leads to an incomplete assessment of HRQL in these patients. Therefore, the objective of the present study was to develop a specific HRQL measurement for patients with severe respiratory insufficiency receiving HMV, thereby identifying relevant domains of HRQL in these patients.

Section snippets

Patients and study design

The study protocol was approved by the institutional review board for human studies, and informed written consent was obtained from all patients. The patients were recruited from four German hospitals: University of Freiburg (n = 30), Krankenhaus Göttingen-Weende, Lenglern (n = 93), Krankenhaus Grosshansdorf (n = 60), Thoraxklinik-Heidelberg (n = 51). All patients had hypercapnic chronic respiratory failure, and had been therefore established on noninvasive HMV prior to enrolment using

Results

All patients enrolled were fully conversant with HMV, and were clinically stable with no signs of acute exacerbation. Eight patients were excluded from the study, because they did not complete the questionnaires. The characteristics of the 226 patients enrolled are given in Table 1. Seventy-eight patients had COPD, 57 patients had idiopathic kyphoscoliosis, 20 patients had posttuberculosis sequelae, 49 patients had neuromuscular diseases (Duchenne muscular dystrophy, n = 17; polyneuropathy, n = 13;

Discussion

The SRI Questionnaire is a new specific measure of HRQL in patients receiving HMV who suffer from advanced respiratory failure due to various underlying diseases. The SRI was developed following a validation study including 226 patients with severe respiratory insufficiency receiving HMV, and, to our knowledge, this is the largest study working on HRQL in patients receiving HMV.

In the present study the SRI has been demonstrated to have encouraging psychometric properties. The reliability of the

Acknowledgements

The study was supported by Breas® Medical AB.

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