Abstract
The health-related quality of life and emotional distress among mothers of sons with Duchenne or Becker muscular dystrophies (n=82) were compared to sex and age group-matched controls (n=26). Participants self-reported health-related quality of life for themselves and their son(s), emotional distress, and mood/anxiety-related medication. Mothers reported poorer health-related quality of life across all domains of their health-related quality of life, as well as higher levels of emotional distress. Clinically elevated symptoms of anxiety were reported by 39% of mothers. Mothers’ report of poorer health-related quality of life for their son(s) was a significant predictor of worse health-related quality of life and emotional distress for themselves across most domains. Additionally, older age of mothers predicted greater energy/less fatigue and lower levels of anxiety. Results highlight the need for screening emotional distress among mothers, as well as consideration for accessible interventions to improve the psychosocial functioning among these families.
Keywords: quality of life, anxiety, depression, muscular dystrophy, caregiving
Muscular dystrophy, including Duchenne and Becker muscular dystrophy, is characterized by progressive muscle weakness and loss of muscle mass due to a X-linked mutation in the DMD gene (dystrophin, locus Xp21.2) that effects the expression of translated protein, dystrophin, in skeletal and cardiac muscle, and gastrointestinal smooth muscle.1 The skeletal muscle loss results in loss of ambulation between 9-13 years of age and death during early adulthood.2 Becker is typically less severe with some individuals not experiencing symptoms until adulthood and death occurring in the fourth or fifth decade of life.3 Significant multisystem complications arise over time for individuals with DMD mutations, including respiratory muscle weakness, loss of gastrointestinal motility, and heart failure.2,4 DMD gene mutations, especially those that potentially disrupt dystrophin isoforms Dp140 and Dp71, have been implicated as the cause for emotional and cognitive symptoms among individuals with dystrophinopathies.5-7 Rates of obsessive compulsive disorder and elevated anxiety symptoms are estimated in 14-29% of boys with Duchenne6,8 or Becker9. Additionally, cognitive impairment has been reported, including problems with verbal working memory and overall IQ.5,6,10
Due to medical advancements, individuals with Duchenne are now ambulating 2-3 years longer and living into their twenties.11-13 The need for supportive care remains a necessity, particularly after loss of ambulation. The routine of 24-hour care may include assistance with meal preparation and feeding, toileting, bathing and dressing, turning in bed during the night, as well as transportation to medical appointments (e.g., routine check-ups, physical therapy, infusions) and school. Individuals with Duchenne receive a majority of their care informally from family members, particularly parents.14 As boys with Duchenne age into adolescence and gain weight, physical demands of caregiving increase, which may be particularly difficult as their caregivers also age. Families also experience the slow decline in health and eventual premature death of their child, taking a tremendous toll on the emotional wellbeing of caregivers.
A recent systematic review of 21 research articles across 15 countries identified multiple negative self-reported outcomes among those providing informal care for individuals with Duchenne, including lower health-related quality of life, pain, and depression.15 Landfeldt and colleagues15 highlighted the physical and emotional consequences of caregiving reported by families. The studies included in the systematic review compared caregiver’s self-report to ratings provided by individuals with Duchenne, national norms, or measure norms. None of the studies included in the systematic review compared caregivers to age and sex-matched healthy controls. Caregivers may vary widely in age, and both age and sex differences exist on self-reported health-related quality of life and emotional distress.16,17
The aim of the current cross-sectional study was 1) to examine differences between mothers who have living sons with Duchenne and Becker muscular dystrophies (mothers) and age and sex group-matched controls on health-related quality of life and emotional distress, and 2) explore demographic and son-related factors that may contribute to poorer health-related quality of life and greater emotional distress. We hypothesized that mothers would report poorer health-related quality of life and greater emotional distress, as well as more use of psychotropic medication, as compared to age- and sex-matched controls. The design of the current study would be independent of the DMD gene mutations since mothers included both somatic and germ-line carriers.
Methods
Participants
This study was part of a larger investigation of the neuromuscular, cardiovascular, emotional, and cognitive functioning of mothers. Potential participants were prospectively recruited from Nationwide Children’s Hospital Neuromuscular Clinic where their sons receive evaluation and treatment, as well as are potentially participating in clinical trials (ClinicalTrials.GovNCT03375164, Nationwide Children’s Hospital) and Parent Project Muscular Dystrophy (Care for Carriers). Women were eligible for participation in the current study if they 1) had at least one living son with a validated DMD gene mutation (Duchenne or Becker), 2) were at least 18 years of age, 3) were able to read and write proficiently in English, and 4) did not have a diagnosis of a neurological condition. Given that dystrophinopathies have a clinical spectrum and not easily classified into distinct categories,18-20 mothers with sons diagnosed with either Duchenne or Becker were grouped together. Age and sex group-matched control participants responded to an email solicitation sent to employees of the same hospital. Control participants were deemed eligible if they 1) did not have any children who were experiencing a chronic medical condition, 2) were at least 18 years of age, and 3) did not have a chronic health condition.
Procedures
In addition to neuromuscular and cardiovascular evaluation, participants underwent neurocognitive screening and completed self-report measures via REDCap21, an online survey platform. The study protocol was completed in-person over the course of two days, and participants had the option of completing the online surveys off-site. All participants provided written consent. The study was approved by the Institutional Review Board at Nationwide Children’s Hospital (IRB16-00319).
Measures
Health-Related Quality of Life
The Research and Development Corporation 36-Item Health Survey 1.0 (RAND-36)22 is a commonly used self-report of health-related quality of life that contains eight subscales: Physical Functioning, Pain, Role Limitations due to Physical Health, Role Limitations due to Emotional Problems, Emotional Well-Being, Social Functioning, Energy/Fatigue, and General Health. Scores can range from 0-100 with higher scores indicating better health-related quality of life. In the current study, each subscale demonstrated good to excellent internal consistency (α = .76-.88). The SF-12, a shorter version of the measure, has been used among caregivers of individuals with Duchenne.14
Mothers also rated their sons’ health-related quality of life using the Generic Core Scales of the Pediatric Quality of Life Inventory Version 4.0 for their children who were at least 2 years of age.23 This tool is another commonly used tool for assessing health-related quality of life among children and adolescents, as reported by a parent. The version of the Pediatric Quality of Life Inventory for 2- to 4-year-olds only has 21 items, whereas the versions for other age groups (ages 5-7, 8-12, 13-18, and 18-25) have 23 items, all of which are on a 5-point Likert scale (i.e., 0-4). Item scores are linearly transformed to a 0-100 scale. There are five subscales that can be derived; however, for the current study only the total score across all items was utilized so that the total could be compared across the age ranges of the sons. If a mother reported having more than one living son with Duchenne or Becker, the average score was calculated across children. The internal consistency across age groups for the total score of the measure in the current study was very good to excellent (α = .74-.91).
Emotional Distress
The 14-item Hospital Anxiety and Depression Scale24 is another commonly used self-report measure that can identify clinical elevations in anxiety and depressive symptoms. Items use a 4-point Likert scale, and scores range from 0 to 21 with the following scores as indicating varying symptom levels: ≥10.5 = definite cases and ≤10.4 = doubtful and non-cases.24 For the current study, both the anxiety (α = .87) and depression (α = .80) subscales had very good internal consistency. This instrument has also been used to assess emotional distress in caregivers of individuals with Duchenne.25
Perceived stress was measured using the Perceived Stress Scale, a widely used measure of the degree to which situations in one’s life are perceived as stressful.26 The measure consists of 10 items that use a 5-point Likert scale, with scores ranging from 0-40. In the current study, the Perceived Stress Scale demonstrated high internal consistency (α = .89). This instrument has been used among caregiving parents of children undergoing stem cell transplant27 and children with autism or attention deficit hyperactivity disorder.28
Participants also self-reported current mood and anxiety-related medications. If a participant was taking a medication that fell within the categories of antidepressants, anxiolytics, and mood stabilizers, she was counted as a “1”, as opposed to not taking any of these types of medications (“0”). Cognitive-enhancing medications, such as atomoxetine (Strattera®), and sleep aides were not included.
Data Analysis Plan
Self-report data was missing only on the Pediatric Quality of Life Inventory for two of the mothers. One mother did not complete that portion of the survey and the other had a son who was <2 years of age. To address the first aim of the study, chi-squares and t-tests were employed to examine differences between mothers and controls on demographic variables and measures of health-related quality of life and emotional distress. For aim 2, first Pearson correlations were used to determine the relationship between demographic variables and measures of health-related quality of life and emotional distress among mothers. Demographic factors that were significantly correlated with mothers’ health-related quality of life and emotional distress were then included in a linear regression model for each outcome to determine which variable accounts for the most variability in that outcome. For the 2 mothers missing responses on the Pediatric Quality of Life Inventory for their sons, they were eliminated from analyses due to listwise deletion. P values <.05 were considered statistically significant.
Results
Differences between mothers and controls on demographic variables, health-related quality of life, and emotional distress
The final sample included 82 mothers and 26 controls. Of the mothers included in the current study, three had only partial data. As can be viewed in Table 1, mothers did not differ from controls on age, race, highest education achieved, or family income. A majority of the mothers reported having one affected son (88%) with the mean age of affected sons being approximately 9 years of age. Of note, due to an online survey error, the age of affected sons was missing in 10 surveys.
Table 1.
Demographics, health-related quality of life, and emotional distress outcomes for mothers and controls.
| Mothers (n = 82) | Controls (n = 26) | χ2 or t | P | d | |
|---|---|---|---|---|---|
| Mean ± SD (Range) or % | |||||
| Age | 40.40±6.98 (27-63) | 42.27±7.02 (30-59) | −1.04 | .300 | .24 |
| Race | 0.75 | .386 | |||
| White | 94% | 92% | |||
| Other | 6% | 8% | |||
| Highest Education | 4.21 | .240 | |||
| High School/GED/Technical | 13% | 4% | |||
| College | 51% | 42% | |||
| Graduate/Professional | 36% | 54% | |||
| Family Income (per year) | 4.87 | .301 | |||
| ≤ $25,000 | 5% | 0% | |||
| $25,001 – $50,000 | 17% | 4% | |||
| $50,001 – $75,000 | 15% | 24% | |||
| $75,001 – $100,000 | 29% | 36% | |||
| $100,001+ | 34% | 36% | |||
| Diagnosis of Son(s) | N/A | N/A | |||
| Duchenne | 87% | N/A | |||
| Becker | 13% | N/A | |||
| # Living Sons with Duchenne/Becker | N/A | N/A | |||
| 1 | 88% | N/A | |||
| 2 | 12% | N/A | |||
| Age of Son(s)† | 9.04±5.93 (1-27) | N/A | |||
| Marital Status | 1.49 | .914 | |||
| Single | 2% | 4% | |||
| Married/Remarried/Living w/ Someone | 92% | 88% | |||
| Separated/Divorced | 6% | 8% | |||
| Demographics, health-related quality of life, and emotional distress outcomes for MDB and Controls. | |||||
| MDB (n = 82) | Controls (n = 26) | t | P | d | |
| Mean±SD (Range) or % | |||||
| Taking a Mood/Anxiety-Related Medication | 24% | 31% | 0.46 | .497 | |
| RAND-36 | |||||
| Physical Functioning | 82.87±18.64 (10-100) | 96.35±5.01 (85-100) | −5.91 | <.001 | .99 |
| Role Limitations - Physical | 76.83±32.58 (0-100) | 96.15±9.20 (75-100) | −4.80 | <.001 | .81 |
| Role Limitations - Emotional | 67.89±36.83 (0-100) | 84.62±28.64 (0-100) | −2.41 | .019 | .51 |
| Energy/Fatigue | 47.48±21.69 (0-95) | 57.69±21.08 (5-85) | −2.11 | .038 | .48 |
| Emotional Well-Being | 66.06±17.13 (12-92) | 74.27±16.66 (32-96) | −2.14 | .034 | .49 |
| Social Functioning | 76.52±21.55 (12.5-100) | 90.87±15.64 (37.5-100) | −3.14 | .002 | .76 |
| Pain | 77.47±19.68 (22.5-100) | 87.40±12.60 (57.5-100) | −3.02 | .004 | .60 |
| General Health | 66.58±20.73 (15-100) | 79.42±16.14 (35-100) | −2.89 | .005 | .69 |
| Hospital Anxiety and Depression Scale | |||||
| Total Anxiety Score | 9.61±4.29 (0-19) | 6.88±3.80 (1-13) | 2.90 | .005 | .67 |
| Total Depression Score | 4.87±3.38 (0-15) | 3.06±3.19 (0-10) | 2.41 | .018 | .55 |
| Perceived Stress Scale | 16.83±6.75 (2-33) | 13.19±6.71 (2-31) | 2.40 | .018 | .54 |
| Pediatric Quality of Life Inventory Total Score for Sons‡ | 57.60±17.56 (7.61-100) | N/A | N/A | N/A | |
d = Cohen’s d effect size (.2 = small, .5 = medium, .8 = large); GED = General Education Development test; RAND-36 = Research and Development Corporation 36-Item Health Survey; SD = standard deviation; t = t-test statistic
Age of son(s) was missing for 10 MDB due to an error in the online survey during data collection.
The Pediatric Quality of Life Inventory total score was missing for 1 mother due to an incomplete survey, and for another mother because her son was <2 years of age.
Per the t-test results, also reported in Table 1, mothers reported significantly poorer health-related quality of life across all subscales of the RAND-36. As can be seen by the effect sizes listed in Table 1 (d), pronounced differences were found between mothers and controls on Physical Functioning, Role Limitations – Physical, and Social Functioning subscales. Additionally, mothers reported higher levels of anxiety and depressive symptoms, as well as perceived stress. The percent of mothers and controls who reported clinically elevated symptoms of anxiety and depression can be seen in Table 2. Clinically elevated symptoms of anxiety were reported by 39% of mothers, as compared to 19% controls, though the proportion of women who reported clinically elevated symptoms of depression did not statistically differ between the groups. The proportion of mothers who reported taking at least one mood/anxiety-related medication did not differ from controls.
Table 2.
Clinically relevant cut-offs for anxiety and depressive symptoms among mothers and controls for the Hospital Anxiety and Depression Scale
| Mothers (n=82) | Controls (n=26) | |||||
|---|---|---|---|---|---|---|
| n(%) | n(%) | χ2 | P | |||
| Definite Cases |
Doubtful and Non- Cases |
Definite Cases |
Doubtful and Non- Cases |
|||
| Anxiety | 32(39%) | 50(61%) | 5(19%) | 21(81%) | 3.43 | .064 |
| Depressive | 6(7%) | 76(93%) | 0(0%) | 26(100%) | 2.01 | .156 |
χ2= Chi-square statistic
Factors contributing to mothers’ reports of poorer health-related quality of life and emotional distress.
Multivariate linear regressions, which included mother’s age, the number of affected sons, mean sons’ age, and the mother’s report of the sons’ health-related quality of life as predictors of her health-related quality of life and emotional distress. The surveys missing the age of the affected son(s) were excluded from the regressions due to listwise deletion. For health-related quality of life, which can be found in Table 3, mothers’ report of sons’ health-related quality of life was the only significant factor explaining variance in mothers’ health-related quality of life for all subscales, except Role Limitations – Emotional and Energy/Fatigue, indicating that when mothers report that their son(s) have higher health-related quality of life, they also report higher health-related quality of life across most domains of the RAND-36. None of the variables included explained a significant amount of variance in Role Limitations – Emotional health-related quality of life. For Energy/Fatigue, age of the mother was also predictive, suggesting that being older was associated with higher energy/less fatigue. A similar pattern of results was identified for emotional distress, such that mothers’ report of poorer health-related quality of life for their son(s) was a significant predictor of greater depressive symptoms and perceived stress (Table 4). Mothers’ report of their sons’ health-related quality of life was not predictive of their own anxiety symptoms. However, older age for mothers was predictive of fewer anxiety symptoms.
Table 3.
Results of linear regressions for the contribution of age, number of living sons diagnosed with Duchenne or Becker, sons’ age, and sons’ health-related quality of life (Pediatric Quality of Life Inventory) on mothers’ health-related quality of life (RAND-36).
| B | SE | β | 95% CI | Adj R2 | |
|---|---|---|---|---|---|
| Physical Functioning | .18 | ||||
| Age | −.15 | .47 | −.06 | −1.08, .78 | |
| # of Sons | 9.26 | 6.44 | .16 | −3.60, 22.11 | |
| Sons’ Mean Age | −.82 | .59 | −.26 | −2.01, .36 | |
| Sons’ Quality of Life | .27 | .14 | .25 | .00, .54 | |
| Role Limitations - Physical | .10 | ||||
| Age | −.83 | .84 | −.18 | −2.52, .85 | |
| # of Sons | 9.72 | 11.63 | .10 | −13.51, 32.95 | |
| Sons’ Mean Age | −.15 | 1.07 | −.03 | −2.29, 1.99 | |
| Sons’ Quality of Life | .53 | .24 | .29 | .05, 1.02 | |
| Role Limitations - Emotional | −.01 | ||||
| Age | .97 | 1.07 | .18 | −1.16, 3.11 | |
| # of Sons | 17.47 | 14.74 | .15 | −11.96, 46.89 | |
| Sons’ Mean Age | −0.79 | 1.36 | −.12 | −3.50, 1.92 | |
| Sons’ Quality of Life | .19 | .31 | .09 | −.42 .81 | |
| Energy/Fatigue | .13 | ||||
| Age | 1.26 | .57 | .40 | .13, 2.39 | |
| # of Sons | 9.72 | 7.81 | .14 | −5.89, 25.32 | |
| Sons’ Mean Age | −.61 | .72 | −.16 | −2.04, .83 | |
| Sons’ Quality of Life | .34 | .16 | .27 | .01, .67 | |
| Emotional Well-Being | .11 | ||||
| Age | .76 | .46 | .30 | −.15, 1.68 | |
| # of Sons | 4.20 | 6.31 | .08 | −8.40, 16.79 | |
| Sons’ Mean Age | .10 | .58 | .03 | −1.06, 1.26 | |
| Sons’ Quality of Life | .31 | .13 | .31 | .05, .58 | |
| Social Functioning | .08 | ||||
| Age | .01 | .59 | .00 | −1.16, 1.18 | |
| # of Sons | 12.37 | 8.07 | .18 | −3.75, 28.50 | |
| Sons’ Mean Age | .44 | .74 | .12 | −1.04, 1.93 | |
| Sons’ Quality of Life | .46 | .17 | .36 | .13, .80 | |
| Pain | .11 | ||||
| Age | .04 | .51 | .01 | −.98, 1.06 | |
| # of Sons | 11.62 | 7.05 | .19 | −2.46, 25.70 | |
| Sons’ Mean Age | −.27 | .65 | −.08 | −1.56, 1.03 | |
| Sons’ Quality of Life | .38 | .15 | .33 | .08, .67 | |
| General Health | .13 | ||||
| Age | .81 | .53 | .27 | −.26, 1.87 | |
| # of Sons | −.64 | 7.33 | −.01 | −15.28, 14.00 | |
| Sons’ Mean Age | −.77 | .68 | −.22 | −2.12, .58 | |
| Sons’ Quality of Life | .41 | .15 | .35 | .11, .72 |
Adj = adjusted; B = unstandardized beta coefficient; β = standardized beta coefficient; CI = confidence interval; RAND-36 = Research and Development Corporation 36-Item Health Survey; SE = standard error for the unstandardized beta
Table 4.
Results of linear regressions for the contribution of age, number of living sons diagnosed with Duchenne or Becker, sons’ age, and sons’ health-related quality of life (Pediatric Quality of Life Inventory) on mothers’ emotional distress (Hospital Anxiety and Depression Scale and Perceived Stress Scale).
| B | SE | β | 95% CI | Adj R2 | |
|---|---|---|---|---|---|
| Anxiety Symptoms | .09 | ||||
| Age | −.25 | .11 | −.42 | −.47, −.03 | |
| # of Sons | .78 | 1.49 | .06 | −2.21, 3.76 | |
| Sons’ Mean Age | .07 | .14 | .10 | −.21, .34 | |
| Sons’ Quality of Life | −.05 | .03 | −.19 | −.11, .02 | |
| Depressive Symptoms | .07 | ||||
| Age | −.04 | .09 | −.09 | −.23, .14 | |
| # of Sons | −.57 | 1.29 | −.05 | −3.14, 2.00 | |
| Sons’ Mean Age | −.07 | .12 | −.12 | −.31, .17 | |
| Sons’ Quality of Life | −.07 | .03 | −.37 | −.13, −.02 | |
| Perceived Stress | .25 | ||||
| Age | −.31 | .16 | −.33 | −.62, .00 | |
| # of Sons | .21 | 2.16 | .01 | −4.10, 4.53 | |
| Sons’ Mean Age | −.17 | .20 | −.15 | −.56, .23 | |
| Sons’ Quality of Life | −.17 | .05 | −.46 | −.26, −.08 |
Adj = adjusted; B = unstandardized beta coefficient; β = standardized beta coefficient; CI = confidence interval; SE = standard error for the unstandardized beta
Discussion
The current study is the first to report health-related quality of life and emotional distress symptoms among mothers who have living sons with Duchenne and Becker muscular dystrophies as compared to sex and age group-matched controls, as well as examine the relative contribution of mothers’ report of sons’ health-related quality of life on their own ratings of health-related quality of life and emotional distress. Results suggested that as compared to women of similar demographics, mothers report significantly worse health-related quality of life and greater emotional distress, including high levels of clinically elevated anxiety symptoms. Furthermore, mothers’ perception of their sons’ health-related quality of life is a significant predictor of their own health-related quality of life and emotional distress across multiple domains.
Large effect sizes were found for differences in Physical Functioning, Role Limitations – Physical, and Social Functioning subscales of the RAND-36 between mothers and controls. This may be due, in part, to mothers performing the transfers for their sons, who as they age get larger, are less able to assist, and could be overweight as a side effect of corticosteroid treatment.29 Another consequence of the physical wear-and-tear of caregiving may be reflected in the differences identified on the Social Functioning subscale. Mothers report that their physical and emotional health interferes with social activities, which is an important component of stress management among caregiving parents.30,31
In addition to poorer health-related quality of life, mothers also reported more symptoms of anxiety and depression, as well as greater perceived stress as compared to controls. Of particular concern was the finding that 39% of mothers reported clinically elevated symptoms of anxiety. Pangalila and colleagues25 found that 21% of 80 Duchenne caregivers from the Netherlands reported clinically elevated depressive or anxiety symptoms using the Hospital Anxiety and Depression Scale. Higher rates of depression (32%) and panic/anxiety attacks (31%) were also found in a German sample of 248 caregivers, though no validated measure of emotional distress was utilized.32 Similarly, 32% of the 39 Duchenne caregivers in the United Kingdom exceeded the clinical cut-off for psychiatric risk using the General Health Questionnaire, but similar to the current study, this rate did not differ from controls.33
Given the notable levels of distress found in the current study and in other published research among caregivers, attention should be paid towards screening and intervention that may serve the entire family. In fact, care guidelines for Duchenne recommend proactive psychosocial assessment of both caregivers and families.2 However, there are notable barriers to screening and intervention among adult caregivers worth mentioning. First, given that many Duchenne centers are housed within pediatric hospitals, mental health service providers who offer psychosocial interventions for the family may not have the training or resources to provide individual treatment for adult caregivers. Furthermore, referrals for providers in the community require additional appointments that could increase burden on families who are already juggling medical and physical therapy appointments for their affected son(s). These barriers may deter medical teams from screening for emotional distress among mothers. Despite these limitations, several brief screening instruments are available that can be used in a clinic setting. The Hospital Anxiety and Depression Scale24 (14 items) and the Patient Health Questionnaire – 934 (9 items) have been validated in multiple medical populations that have clinical cutoffs to guide medical staff on the need for referral. Neither of these instruments require administration by a trained mental health professional. If a referral is warranted, and an appropriate provider is not available at the institution in which the son is treated, caregivers can be encouraged to identify a provider through their insurance company. Additional research is needed to assess the optimal modality by which to address both the psychosocial needs of mothers and their sons, preferably in the same medical system in which the son receives treatment to reduce burden on families. As evidenced by the recently published results of a randomized clinical trial to reduce anxiety disorder symptoms in children, treating the parents is as efficacious as treating the children directly.35 Furthermore, the investigators noted that parent-based therapies may be particularly useful when the child has communication difficulties or significant development delays.
The current study also examined several potentially relevant factors that could contribute to mothers’ report of poorer health-related quality of life and emotional distress. Mothers’ perceptions of their son(s)’ health-related quality of life explained unique variance across almost all of the components measure for health-related quality of life and emotional distress. Nereo and colleagues reported greater stress among mothers related to their interactions with their sons’ behavior as compared to a normative group, particularly in the realm of social problems.36 Given that emotional wellbeing and social functioning is a component of the Pediatric Quality of Life Inventory, our findings may be echoing those of Nereo and colleagues in reflecting increased stress due to difficult interactions with the son. However, given the emotional toll of physical decline, which is also reflected in the Pediatric Quality of Life Inventory, mothers’ perception of the overall wellbeing of her son may be an important driver in her perception of her own wellbeing. Notably, the number of affected sons and the age of the son(s) did not significantly contribute to any of the models. Other studies have also found no association with caregiver strain and patient characteristics, such as the age of the patient.37
Older age for mothers was another significant contributor to models explaining variance in better energy and fatigue levels and lower levels of emotional distress (i.e., anxiety symptoms). The finding that older age is associated with lower levels of emotional distress is expected given there is evidence supporting remission for major depressive disorder and generalized anxiety disorder with increasing age.38 This may be due to improved coping over time for these women, though longitudinal research is needed to determine if that is the mechanism by which to explain this relationship. Lower levels of emotional distress among older mothers may also explain the relationship between age and energy/fatigue. It is well-established that emotional distress is closely tied to the experience of fatigue in adults, particularly among women.39 Therefore, younger age may be viewed by medical teams as a potential risk factor for emotional distress, which could present as low energy/fatigue.
Age of the son(s) is another factor that has been considered when examining caregiver outcomes, particularly because as the son ages, impact of the disease increases placing more demands on caregivers. However, findings have been equivocal. One study of 31 Duchenne caregivers in Brazil concluded that an older age of the son(s) was associated with greater perceived caregiver burden.40 In contrast, a recent study by Lue and colleagues41 did not find a correlation between sons’ age and self-reported health-related quality of life of caregivers. Their sample included caregivers of boys with Becker and limb girdle dystrophies, which may have included more variability in caregiver demands. In the current study, older son(s)’ age did not significantly contribute to the variability in outcomes among caregivers.
There are several notable limitations of the current study to consider. First, the control group consisted predominantly of nursing staff. Nursing staff are not representative of the general population, particularly in education level and income. However, participating mothers also had relatively high levels of education and income, which matched the control group well. Furthermore, many of the members of the control group work in a high-stress hospital environment, which is prone to burnout,42 making the identified differences between mothers and controls all the more striking. If compared to women from the general population, differences in health-related quality of life and emotional distress may have been even larger. Second, the sample size was relatively small, particularly for the control group. While the sample size allowed for the detection of several large effect sizes when comparing mothers to controls, as well as significant predictors of poorer health-related quality of life and emotional distress, it limited the number of variables that could be included in the regression model before inflating Type 2 error. Additional factors that were not the focus of the current study, such as mothers’ education and/or income, have been associated with poorer health-related quality of life and emotional distress among muscular dystrophy caregivers,41 as well as in other populations.43,44 ANOVAs were conducted to examine whether health-related quality of life or emotional distress varied by level of education or income and no differences between education or income level were identified. Therefore, they were not added to the regression models. Lastly, the current study only had access to mothers’ report of sons’ health-related quality of life rather than the sons’ self-report. Bray and colleagues 45 reported that the agreement between parent-report of their sons and self-report of sons with Duchenne using the Pediatric Quality of Life Inventory was moderate to poor. Therefore, the current study is not likely capturing how sons viewed their health-related quality of life. However, when attempting to determine what contributes to poorer health-related quality of life and emotional distress among mothers, knowing mothers’ perception of their sons’ health-related quality of life may be the most important factor to consider, regardless of alignment with the sons’ report of their health-related quality of life.
Conclusion
Mothers reported poorer health-related quality of life and greater emotional distress as compared to women of similar age and socioeconomic background. The alarmingly high rate of clinically elevated anxiety symptoms, in conjunction with care guidelines recommending psychosocial assessment and treatment for families of boys with Duchenne,2 points to the need for family-based interventions. Additional research must identify efficacious family-based interventions that reduce anxiety levels among mothers. Furthermore, better understanding the relationship between mothers’ perceptions of their sons’ health-related quality of life and their own health-related quality of life and emotional distress may help medical teams identify mothers who are at risk for poorer psychosocial outcomes and offer timely resources. Duchenne and Becker muscular dystrophies are conditions that affect the entire family,15 and therefore necessitate treating the entire family.
Acknowledgements
We would like to thank the families who participated in the current study, which for many included traveling.
Funding
This work was supported by Parent Project Muscular Dystrophy (PIs: M.L. Mah and J. Mendell), The Heart Center at Nationwide Children’s Hospital (PI: M.L. Mah), and Clinical and Translational Science Award (grant number UL1TR001070) to The Ohio State University and Nationwide Children’s Hospital.
Footnotes
Declaration of Conflicting Interests
None to report.
References
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