Emotional Distress, Barriers to Care, and Health-Related Quality of Life in Sickle Cell Disease

Journal of Clinical Outcomes Management. 2015 January;January 2015, VOL. 22, NO. 1:

January 20, 2015|Journal of Clinical Outcomes Management

Marsha J. Treadwell, PhD;Fernando Barreda, BA;Kimpreet Kaur, BS;Ginny Gildengorin, PhD

Symptoms of Anxiety

Participants completed the Generalized Anxiety Disorder 7-item (GAD-7) questionnaire for screening and measuring severity of generalized anxiety disorder [39]. The GAD-7 asks about such symptoms as feeling nervous, anxious, or on edge over the past two weeks. Scores from all 7 items are added to obtain a total score [40]. Cut-points of 5, 10, and 15 represent mild, moderate, and severe levels of anxiety symptoms. Respondents indicate how difficult the symptoms make it for them to engage in daily activities from 0 (Not difficult at all) to 3 (Extremely difficult). The internal consistency of the GAD-7 is excellent (α = 0.92). Test-retest reliability is also good (Pearson r = 0.83) as is procedural validity (intraclass correlation = 0.83). The GAD-7 has excellent sensitivity and specificity to identify generalized anxiety disorder [41].

Health-Related Quality of Life

Participants completed the SF-36, which asks about the patient’s health status in the past week [14]. Eight subscales include physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional and mental health. Two summary measures, the Physical Component Summary and the Mental Component Summary, are calculated from 4 scales each. Use of the summary measures has been shown to increase the reliability of scores and improve the validity of scores in discriminating between physical and psychosocial outcomes [14]. Higher scores represent better HRQL, with a mean score of 50 (SD = 50) for the general population. Internal consistency estimates for the component summary scores are α > 0.89, item discriminant validity estimates are greater than 92.5% and 2-week test-retest reliability was excellent. Scores on the SF-36 have been divided into categories of HRQL functioning [42,43]. Participants in the impaired to very impaired category have scores ≤ mean – 1 SD while participants with average to above average functioning have scores > mean – 1 SD.

The SF-36 has been used extensively in observational and randomized studies for a range of illness conditions. In SCD, some aspects of HRQL as measured by the SF-36 improved for adult patients who responded to hydroxyurea [44]. Participants in the Pain in Sickle Cell Epidemiology Study scored lower than national norms on all SF-36 subscales except psychosocial functioning [45]. HRQL decreased significantly as daily pain intensity increased [45]. Further, women reported worse bodily pain compared with men [46].

Data Analyses

All biostatistical analyses were conducted using Stata 13 [47]. Continuous variables were examined for normality with measures of skewness and peakedness. All variables satisfied the assumptions of normality with the exception of barriers to health care and ED utilization. The variable barriers to health care was transformed using a square root transformation, resulting in a more normally distributed variable. ED utilization was dichotomized as 0–2 versus 3 or more ED visits in the previous 12 months, based on the distribution of utilization in the sample. The cutpoint of ≥ 3 annual ED visits is consistent with other literature on SCD clinical severity [48].

Descriptive statistics were computed to include means, standard deviations and frequencies. Sociodemographic variables (age, sex, insurance status [public or private] and income) were examined as potential covariates using Pearson correlations and t tests. Associations among emotional distress (anxiety and depression symptoms), clinical complications and ED utilization, barriers to health care, and the outcomes of the Physical and Mental Component Summary scores from the SF-36 were examined using Pearson correlations. We conducted stepwise regression with forward selection to determine models predictive of physical and mental HRQL. We tested the addition of each chosen variable (anxiety symptoms, depression symptoms, clinical complications, ED utilization, barriers to health care, age, sex, insurance status, and income), adding the variables (if any) that were most correlated with the outcome, and repeated the process until the model was not improved. A significance level of 0.05 was used for all statistical tests.

Results

Demographic and Clinical Characteristics

Table 1 shows the demographic characteristics of the 77 participating adults with SCD. Sixty percent were female. Patients ranged in age from 18 to 69 years, with a mean age of 31.6 (SD = 13.1) years. Consistent with the general SCD population, participants were predominantly black/African American. Over 66% of families reporting had a median household income of less than $30,000 annually, although the mean household size was 3 to 4 persons. The majority of the participants (57%) had some college and beyond, although 14% had not completed high school. Over 80% of participants were on public insurance.

The majority of patients (73%) were diagnosed with Hgb SS disease and the most common lifetime complication was pain, reported by almost all of participants (Table 1). The next most common complication was fever, followed by acute chest syndrome. Twenty-seven percent of participants were currently on the disease-modifying therapy hydroxyurea, while 61% had a lifetime history of transfusion therapy. These data were verified with information from the clinical database for 73 participants (95%).

The median number of ED visits in the previous year was 1 (range, 0–50), with 19 patients (25%) with zero visits. The median number of hospital days in the previous year was 13 (range, 0–81). Twenty-nine patients (38%) had no hospital days in the previous year. These data were verified with information from the clinical database for 53 participants (69%), since hospital and ED visits occurred at institutions not always linked with the clinical databases at the sponsoring hospitals.

Emotional Distress, Barriers to Care, and Health-Related Quality of Life

The mean score for the sample on the PHQ-9 was 7.2 (SD = 5.6, α = 0.86, Table 2). The prevalence of moderate to severe symptoms of depression (ie, scores ≥ 10) was 33% (n = 25). Twelve patients with moderate to severe symptoms (48%) reported that symptoms of depression created some difficulty in work, daily activities, or relationships, while 10 patients (40%) reported very much to extreme difficulty in work, daily activities, or relationships due to depression symptoms.

The mean score on the GAD-7 was 7.9 (SD = 6.0, α = 0.90, Table 2). The prevalence of moderate to severe symptoms of anxiety (scores ≥ 10) was 36.4% (n = 28). Fourteen patients with moderate to severe symptoms (50%) reported that anxiety symptoms created some difficulty in work, daily activities, or relationships. Twelve patients (43%) reported that symptoms created very much to extreme difficulty in work, daily activities, or relationships. Fifteen patients (29%) with moderate to severe symptoms of anxiety or depression exhibited comorbid anxiety and depression.

The mean Physical Component Summary score on the SF-36 was 53.6 (SD = 24.1, α = 0.94, Table 2). The prevalence of impaired to very impaired HRQL in the physical domain was 17% (n = 13). The mean Mental Component Summary score on the SF-36 for the sample was 50.1 (SD = 23.7, α = 0.93), with a prevalence of 16% (n = 12) in the impaired to very impaired range for HRQL in the mental domain.

The mean number of barriers from the barriers checklist was 9.2 (SD = 10.1) out of 53 possible. Sixty-five participants (86%) reported at least 1 barrier to accessing health care (Table 2). The most frequently cited barriers to care were provider knowledge and attitudes, followed by transportation, insurance, and access to services (eg, hours and location of services). Less frequently cited barriers to care were individual barriers, including memory, health literacy and motivation, as well as those related to SCD itself, ie, fatigue and pain.

Sociodemographic Variables, Emotional Distress, and Health-Related Quality of Life

Symptoms of anxiety and depression were highly correlated with one another, as would be expected (r = 0.75, P < 0.001). Physical and mental HRQL were significantly correlated with symptoms of depression (r = –0.67, P < 0.001 for physical HRQL component and r = –0.70 for mental HRQL component, P < 0.001), with impaired HRQL in both domains correlated with greater symptoms of depression. Physical and Mental Component Summary scores were significantly correlated with symptoms of anxiety (r = –0.58, P < 0.001 for the physical component and r = –0.62 for the mental component, P < 0.001), with impaired HRQL in both domains correlated with greater symptoms of anxiety. Ratings of difficulty with daily functioning from depressive symptoms were correlated with impaired HRQL in the physical (r = –0.46, P < 0.01) and mental domains (r = –0.52, P < 0.001). Ratings of difficulty with daily functioning from anxiety symptoms were also correlated with impaired HRQL in the physical (r = –0.58, P < 0.001) and mental domains (r = –0.63, P < 0.001). Reports of more barriers to health care were significantly correlated with reports of more depressive and anxiety symptoms (r = 0.53, P < 0.001 and r = 0.48, P < 0.001), with lower Mental Component Summary scores (r = –0.43, P < 0.05), and with more ED visits in the past year (r = 0.43, P < 0.05).

Relations Between Independent Variables and Outcomes

Results of regression analyses (Table 3) indicated that a model including depression symptoms, age, ED utilization, anxiety symptoms and sex predicted the physical component of HRQL (R² = 0.55, F(5, 66) = 15.8, P < 0.001). Increased symptoms of depression, older age and 3 or more ED visits in the previous 12 months were independently associated with lower ratings of physical HRQL, controlling for anxiety and sex. A model including depression symptoms, barriers to care, insurance status, lifetime complications of SCD and sex predicted the mental component of HRQL (R2 = 0.56, F(5, 66) = 16.7, P < 0.001). Increased symptoms of depression were independently associated with lower ratings of mental HRQL, controlling for barriers to care, insurance status, lifetime complications of SCD, and sex.