Prevalence and Impact of Depression and Anxiety in Cystic Fibrosis

Numerous studies have demonstrated that patients with chronic illnesses are at increased risk for depression and anxiety. In large, well-controlled epidemiological studies, rates of depression in medical populations have ranged from 17% to 50% compared to 5% to 17.5% in healthy populations. Reporting on a community-based sample, Wells and colleagues concluded that individuals with a chronic medical condition have a 41% increase in the risk of having a psychiatric disorder as well.

In patients with chronic illnesses, depression and anxiety have been shown to have direct and indirect consequences for health outcomes, and this has been addressed in a recent ATS/ERS consensus statement on pulmonary rehabilitation. Depressed patients are less compliant with medical regimens, less likely to follow dietary regimes, more likely to cancel or miss clinic appointments, report worse functioning on several quality of life domains, have increased health care utilization and higher health care costs, and are also more likely to engage in risky behaviors, such as smoking, drinking and drug use.

To date, studies of the impact of depression and anxiety in patients with CF have been limited by small samples sizes, samples of convenience that may provide biased estimates of symptom rates, and have used measures that confound symptoms of depression with those of a chronic illness. Given the importance of identifying and treating these symptoms, and their implications for long-term health outcomes, the current study proposes to conduct the first national prevalence study of depression and anxiety in CF patients and parent caregivers. Furthermore, we plan to examine the impact of these psychological symptoms on health outcomes, such as pulmonary exacerbations and nutritional status.

1. Anxiety and Depression are common in Cystic Fibrosis, but their exact prevalence is unknown. Specific Aim 1: To estimate the prevalence of depression and anxiety in patients with CF ages 14 to 17 and parent caregivers of those adolescents Of the few studies of school-age children and adolescents with CF, one reported a rate of depression ranging from 11% to 14.5% in contrast to a rate of 2-6% in the general pediatric population. Published rates of anxiety have ranged from 5% to 9% which may approximate that of the general childhood population. Furthermore, the rate of depression in parent caregivers is also high compared to parents of healthy children. In a multi-site adherence intervention trial of 88 parents of young children with CF, ages 1 to 11, 29% of parents scored in the clinical range on a depression screening tool. This is similar to a study of role strain in parents of young children with CF, in which 36.4% of the mothers' depressive symptoms fell within the clinical range. Furthermore, even higher rates of depression were reported in a study of parents soon after the diagnosis, with 64% of mothers and 43% of fathers scoring in the clinical range. Previous estimates of the prevalence of depression and anxiety in patients with CF have been hampered by serious methodological limitations, such as small sample size, convenience sampling that is potentially biased, and the use of diagnostic screening instruments that attribute somatic symptoms to a depressive disorder which may be due to having a chronic illness like CF (e.g., fatigue). Furthermore, studies of depression and anxiety in pediatric CF populations have not considered developmental and gender differences in depression that emerge in the general population during adolescence.
2. Identifying patients and parents at risk for depression and anxiety disorders is important, but risk factors in the CF population are not known. Specific Aim 2: To identify risk factors associated with symptoms of depression and anxiety. This study was cross-sectional, making it impossible for the authors to distinguish whether psychological symptoms preceded or followed patients' employment status, or how either of these might have been related to changes in health outcomes.
3. Anxiety and depression probably lead to worse clinical outcomes in CF, but this has not been evaluated.

Specific Aim 3: To evaluate how depression and anxiety influence health outcomes (particularly number of exacerbations and hospitalizations, FEV1 and nutritional measures) over the ensuing year.

There is wide variability in the progression of disease in patients with CF, as reflected in the distribution of age at diagnosis, age-related pulmonary function, and age at death (Cystic Fibrosis Foundation Patient Registry, 2004). This variability is partially explained by CFTR mutation and gene modifiers, but environmental and sociodemographic factors, and variations in the use of various healthcare interventions are of equal or greater importance in explaining this variability in health outcomes.