Depression is approximately five times more prevalent in patients with sickle cell disease (SCD) than in the general population, and it is significantly associated with worse mental and physical health-related quality-of-life (HRQoL) outcomes, according to a study published in Blood Advances. Health-care use and inpatient costs were also higher in SCD patients with depression than in SCD patients without depression , leading to higher overall health-care expenditures, reported Soheir S. Adam, MD, of the Department of Medicine at Duke University in Durham, North Carolina, and co-authors.
The researchers conducted a prospective study evaluating the relationship between depression and clinical variables, HRQoL outcomes, and use of medical resources among adult patients with SCD receiving regular clinical care at the Duke Adult Comprehensive Sickle Cell Center between February and November 2009.
Patients were excluded from the analysis if they had experienced vaso-occlusive crises (VOC) within the previous 30 days; had an independent current diagnosis of psychosis, depression with psychosis, or a comorbid disorder with psychosis as a primary symptom; were actively abusing alcohol or illegal drugs; or had concurrent chronic systemic disease.
A total of 142 eligible patients (mean age at enrollment = 34.2±12.6 years) completed all study-related testing, including the Beck Depression Inventory (BDI), the self-reported 36-Item Short Form Survey of QoL measures, and a computerized neurocognitive test. Study protocol also asked patients to keep a pain diary recording the time, location, severity, and types of management of painful episodes for one consecutive week each month. Information about use of medical resources and costs was collected for one year prior to study inclusion and during six months of follow-up.
SCD severity was assessed using a modified version of a previously validated chronic disease severity score, where 1 point is given for pulmonary dysfunction, avascular necrosis of the hip or shoulder, central nervous system abnormality, kidney dysfunction, or a history of leg ulcers, with 5 being the highest possible score and representing the most severe disease. Patients had the following disease severity:
- score 0: 34 (24%)
- score 1: 54 (38%)
- score 2: 31 (21.8%)
- score 3: 16 (11.2%)
- score 4: 7 (5%)
More than one-third of patients in the study (n=50; 35%) had some degree of depression, including 37 (26%) with clinical depression (defined as a BDI score ≥14). The remaining 13 patients (9%) had a BDI score <14 but were actively receiving therapy for depression. Women were more likely to be depressed than men (n=26/81 and n=12/59, or 44.4% and 20.3%, respectively; p=0.004). Body mass index, age, and SCD genotype did not appear to be related to depression.
Most patients (87%) reported an annual household income between $2,500 and $25,000; reported income did not differ between those with and without depression. Most patients (60%) received disability benefits, and 25 percent reported being employed.
Hemoglobin (p=0.009) and male sex (p=0.004) were significantly associated with disease severity, but severity scores did not significantly differ between patients with and without depression (1.29±1.08 vs. 1.46±1.16; p=0.72).
Female sex (p<0.001) and receipt of disability benefits (p=0.03) were significantly related to worse physical QoL outcomes, and female sex was also significantly associated with poorer mental QoL outcomes (p<0.001).
The researchers did not observe significant differences in neurocognitive function (including memory, psychomotor speed, reaction time, complex attention, and cognitive flexibility) among those with and without depression.
When looking at use of medical resources, the authors found that the mean number of hospitalizations was not statistically different between patients with and without depression, in either the 12-month period prior to enrollment (1.2 with depression vs. 0.6 without; p=0.06) or the six-month period following enrollment (0.6 vs. 0.4; p=0.35).
However, overall health-care costs were significantly higher in patients with depression during both time periods:
- $30,665 for patients with depression vs. $13,016 for those without in the 12 months prior to depression assessment (p=0.01)
- $13,766 vs. $8,670 in the six months after assessment (p=0.04)
$30,665 for patients with depression vs. $13,016 for those without in the 12 months prior to depression assessment (p=0.01)
$13,766 vs. $8,670 in the six months after assessment (p=0.04)
Both the total inpatient and overall costs were significantly higher for patients with depression, and the adjusted total average costs were 1.9 times higher for patients with than without depression (95% CI 1.2-3.2; p=0.01), the authors reported.
Inpatient costs were a substantial driver of costs, comprising 84 percent of total costs in the year prior to assessment and 74 percent in the six months after assessment in patients with depression; in patients without depression, however, inpatient costs stayed the same, at 58 percent during both time periods.
“Mental health is an integral part of the comprehensive management of this patient population. Our results highlight an important but inadequately studied aspect of SCD,” the authors concluded. “Additional efforts should be exerted for prevention, early diagnosis, and therapeutic intervention to reduce the impact of depression on [patients with] SCD and improve HRQoL outcomes.”
The study is limited by its single-center design. Also, because the researchers enrolled only patients from the clinic, this patient population was more likely to be compliant with clinic visits and have less severe disease, compared with patients who are admitted through the emergency department or day hospital. The trial excluded patients with VOC, which may decrease the generalizability of these outcomes. In addition, the study was unable to ascertain the time of depression, precluding distinction between hospitalizations and events associated with preexisting depression.