Health-related quality of life and its association with mortality in patients receiving long-term mechanical ventilation

Abstract

Background: Long-term mechanical ventilation (LTMV) is a treatment option for patients with severe chronic respiratory failure. The treatment is carried out in patients’ home or in a nursing home, and can completely or partially compensate for their breathing failure. The majority of patients receive ventilation through a mask covering the nose or both mouth and nose (non-invasive), while a small percentage receive ventilation through a tracheostomy, which is an opening in the neck leading directly to the trachea (invasive). The main goal with LTMV is to maintain or increase quality of life and to prolong survival. Previous research examining quality of life and health-related quality of life (HRQoL) in this group have used a large number of different questionnaires, none of which has been sensitive to the specific challenges of living with LTMV. There is limited knowledge about the long-term outcome of LTMV on quality of life, factors associated with changes in HRQoL and the association with mortality. Aims: The overall aim of this thesis was to provide new knowledge about HRQoL in patients treated with LTMV in a six-year follow-up study. To achieve the overall aim, we had to provide a validated Norwegian version of a specific questionnaire to measure HRQoL in patients treated with LTMV. The main aims were to examine changes in HRQoL in patients receiving LTMV, to examine factors associated with changes in HRQoL in relation to socio-demographic background variables, treatment variables and respiratory variables, and to examine mortality in LTMV patients and the associations between HRQoL and mortality. Materials and methods: This thesis was based on data from the Norwegian LTMV Register in West Norway, the Norwegian Patient Register, the Cause of Death Register, and data on patient-reported outcome measures. In 2008, all the potential eligible adult patients on the LTMV Register in three counties in West Norway were requested to participate in the study. Data from this register and the Short Form-36 (SF-36) generic questionnaire were used to examine the psychometric properties of the Norwegian version of the Severe Respiratory Insufficiency (SRI) questionnaire, a specific HRQoL instrument developed together with patients treated with LTMV. All the patients were followed up from 2008 to 2014. Changes in HRQoL in the patients still treated with LTMV were measured by the SRI questionnaire, in relation to socio-demographic background variables, treatment variables and respiratory variables. Mortality and the ability of the SRI questionnaire to predict mortality were measured by adjusting for socio-demographic variables, including age and education level, clinical variables including main disease group, and treatment variables including hours per day on LTMV, time since initiation of LTMV and comorbidity. Data concerning comorbidity was collected from the Norwegian Patient Register and data on mortality was confirmed by the Cause of Death Register. Results: Out of 193 potential patients on the Norwegian LTMV Register, 127 people (66%) agreed to participate in the study in 2008. The patients were categorized into groups according to neuromuscular diseases, chronic obstructive pulmonary diseases, obesity hypoventilation syndrome and chest wall diseases. The mean age was 61.5 years (SD 15.6) and 68 (53.5%) of the patients were male. The most patients received LTMV via a nasal or mouth mask (92%) and 8% received LTMV via a tracheostomy. The Norwegian version of the SRI questionnaire had good reliability and validity. The reliability of was confirmed by Cronbach Alpha between 0.68 and 0.88 for the subscales and 0.94 for the SRI sum score. The validity was confirmed by high correlations between subscales on the SF-36 and SRI questionnaires. In addition, the validity was supported by that the SRI questionnaire was able to confirm known a priori differences among patients receiving LTMV (Paper I). After six years, 60 patients were still receiving LTMV and confirmed their participation in the follow-up study. HRQoL improved significantly in the majority of the patients according to the total SRI sum score and in four subdomains of the SRI questionnaire. Patients reported satisfaction with training, while follow-up from healthcare professionals was associated with changes in HRQoL. Side effects of the treatment such as facial soreness were associated with lower SRI scores and thus changes in HRQoL. Older age was associated with lower HRQoL on SRI physical functioning subscales. Lung function, as measured by high forced vital capacity, was associated with improved HRQoL on the SRI social functioning subscale (Paper Ⅱ). During the 80-month follow-up period, 52 participants died. The highest mortality rate was among patients with chronic obstructive pulmonary disease (75%), followed by patients with neuromuscular disease (46%), obesity hypoventilation syndrome (31%) and chest wall disease (25%). Lower SRI sum scores in 2008 were associated with a higher mortality risk after adjustment for age, education level, time since initiation of LTMV, hours per day on LTMV, comorbidity and disease category. In addition, according to the SRI questionnaire, physical functioning, psychological well-being and social functioning remained significant risk factors for mortality after covariate adjustment (Paper Ⅲ). Conclusions: Based on quality of life as a conceptual framework, this thesis has provided new important knowledge on HRQoL in patients receiving LTMV from a six-year perspective. Improved HRQoL in the majority of the patients also provides new insights for patients and healthcare professionals. Improvements in the subscale related to overall satisfaction with life, reduced anxiety related to breathing, greater capacity among patients to cope with their condition, and contact and relationship with other people are clinically important. There was also an absence of deterioration in the SRI subscales related to physical functioning, respiratory complaints and attendant symptoms, and sleep during six years of ongoing LTMV. From a healthcare perspective, it important that professionals have the potential to influence their patients’ HRQoL by helping to reduce side effects and improve training and followup. A greater awareness of the strong association between HRQoL measured by SRI and mortality provides important new knowledge to healthcare professionals and political decision makers responsible for the treatment and care of people treated with LTMV. These results highlight the need to identify patients with low HRQoL and initiate interventions to improve HRQoL. Future research should focus on developing effective interventions to assist patients in living with LTMV as well as improving HRQoL and prognosis for treatment.