Introduction
Hereditary motor and sensory neuropathy (HMSN) and myotonic dystrophy (MD) are chronic, slowly progressive neuromuscular diseases (NMD) that cause progressive muscle weakness and impact patients' functional abilities and quality of life. The existing literature presents conflicting findings regarding the prevalence of depression and the quality of life in patients with NMD. Additionally, the respiratory function of our patients remains unknown, although literature reports indicate complications related to the respiratory system and shorter life expectancy in certain NMDs.
Aim of the study
The aim of the study was to assess respiratory function, depression, functional abilities, and quality of life in patients with HMSN and MD, and to determine the differences between these two groups of patients. Additionally, we sought to examine the relationship between respiratory function, depression, and functional abilities with the quality of life in patients with neuromuscular diseases.
Subjects and methods
The study included 62 HMSN patients (median age 53.5, range 19–79 years; 38 women) and 50 MD patients (median age 54.0, range 18–77 years; 34 women). Respiratory function was assessed using spirometry and tests of respiratory muscle strength (RMS) (maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), sniff nasal inspiratory force (Sniff)). The Center for Epidemiological Studies-Depression Scale (CES-D) was used to evaluate depression, and their health-related quality of life was assessed using the Short Form Health Survey (SF-36v2) and the Quality of Life in Genetic Neuromuscular Disease Questionnaire (QoL-gNMD), which was translated into Slovenian and validated for its psychometric properties. Using logistic regression, we examined group-difference in presence of depressive symptoms while accounting for age, symptoms duration, and marital status. Multiple linear regression was used to assess the difference in quality of life scores, adjusting for age, gender, and symptoms' duration. Two-way analysis of variance (ANOVA) was used to analyze the association of group with MIP, MEP, and Sniff, accounting for gender. Multiple linear regression was used to analyze the relationship of respiratory function, depressive symptoms, and functional abilities with quality of life.
Results
The HMSN group had, on average, significantly better scores than the MD group on all normalized measures of respiratory function except for TIFF (approximately 17 % absolute difference in spirometry values and 30 % relative difference in muscle strength measurements). The overall proportion of patients with depressive symptoms (CES-D score ≥ 16) was 33 % (HMSN 24 %, MD 44 %; estimated adjusted odds ratio MD vs. HMSN 1.9, 95 % CI 0.8-4.5, p = 0.127). The median value (range) on the FIM-M was 84.0 (35.0–91.0) for the HMSN group and 85.5 (39.0–91.0) for the MD group. There was no significant difference between the groups regarding the total and motor scores on the FIM scale (p = 0.216). However, scores on the FIM-K scale were significantly higher in the HMSN group (p < 0.001). A significant difference between the groups regarding quality of life measures was found only on the Mental health Summary of the SF-36v2 (p < 0.001), although there was a trend towards better quality of life in the HMSN group.
In MD patients, a more negative association between spirometry, RMS values and quality of life was observed, with a significant negative association between MIP/MEP/Sniff values and QoL-gNMD Self-Perception scale scores (b = -3.48, β = -0.33, p = 0.039). In HMSN patients, spirometry and RMS values were not significantly associated with quality of life.
CES-D scores were significantly negatively associated with quality of life measures in both groups. FIM-M scores were significantly associated with SF-36v2 Physical health Summary scores (HMSN: b = 0.36, β = 0.52, p < 0.001; MD: b = 0.46, β = 0.41, p = 0.003), SF-36v2 Mental health Summary scores (HMSN: b = 0.15, β = 0.18, p = 0.050), QoL-gNMD Physical Symptoms scores (HMSN: b = 0.30, β = 0.43, p < 0.001), QoL-gNMD Self-Perception scores (HMSN: b = 0.25, β = 0.30, p = 0.006; MD: b = 0.26, β = 0.24, p = 0.050), and QoL-gNMD Activities and Social Participation scores (HMSN: b = 0.48, β = 0.66, p < 0.001; MD: b = 0.57, β = 0.52, p < 0.001). FIM-K scores were not significantly associated with quality of life in HMSN patients, whereas in MD patients, significant associations were found with QoL-gNMD Physical Symptoms scores (b = -1.40, β = -0.33, p = 0.014) and SF-36v2 Physical health Summary scores (b = -1.43, β = -0.33, p = 0.018).
Conclusions
Respiratory function was found to be better in patients with HMSN. Depressive symptoms were common in both groups; however, there were no significant differences between the groups in terms of the likelihood of developing depressive symptoms. Patients in both groups were similarly independent in daily activities, such as dressing, washing, and walking. Differences were observed in cognitive functioning, with HMSN patients achieving higher scores, though the average scores in both groups were high. A trend toward poorer quality of life was observed in MD patients, but statistically significant differences were only found on the Mental Health Summary of the SF-36v2 questionnaire. Respiratory function was not significantly associated with quality of life, but in MD patients, a trend towards lower quality of life was seen with lower spirometry and respiratory muscle strength measures. Depressive symptoms were associated with poorer quality of life in both groups. Greater independence in daily activities was associated with better quality of life.
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