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Chest, doi:10.1378/chest.06-2474
doi:10.1378/chest.06-2474
(Chest. 2007; 132:231-237)
© 2007 American College of Chest Physicians
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The Association Between Depression, Lung Function, and Health-Related Quality of Life Among Adults With Cystic Fibrosis*

Kristin A. Riekert, PhD; Susan J. Bartlett, PhD; Michael P. Boyle, MD, FCCP; Jerry A. Krishnan, MD, PhD, FCCP and Cynthia S. Rand, PhD

* From the Divisions of Pulmonary and Critical Care Medicine (Drs. Riekert, Boyle, and Rand), and Rheumatology (Dr. Bartlett), Johns Hopkins School of Medicine, Baltimore MD; and the Section of Pulmonary and Critical Care Medicine (Dr. Krishnan), University of Chicago, Chicago, IL.

Correspondence to: Kristin Riekert, PhD, Assistant Professor, Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, 5501 Hopkins Bayview Circle, JHAAC Room 3B.35, Baltimore, MD 21224; e-mail: krieker1{at}jhmi.edu

Abstract

Background: More than 40% of people born with cystic fibrosis (CF) now reach adulthood. Greater attention is being focused on improving their health-related quality of life (HRQoL). While markers of disease severity such as lung function are only modestly associated with HRQoL, in other chronic illnesses depression is an important correlate. The objective of this study was to evaluate the relationships among lung function (ie, FEV1 percent predicted), depressive symptoms, and HRQoL among adults with CF.

Methods: Seventy-six adults with CF completed a mail-based survey. The Beck Depression Inventory and the Cystic Fibrosis Questionnaire were used to assess depressive symptoms and HRQoL, respectively. Values for FEV1 percent predicted were abstracted from the medical record.

Results: Thirty percent of participants screened positive for depressive symptoms. Depressive symptoms and lung function were inversely correlated (rho = –0.25; p < .05). Correlations between depressive symptoms and HRQoL were maintained after stratifying by lung function. In the absence of depressive symptoms, those patients with good lung function (ie, FEV1, > 70% predicted) reported better physical HRQoL than those with poor lung function. Participants with both depressive symptoms and poor lung function reported significantly worse HRQoL on all domains than participants without depressive symptoms regardless of lung function status.

Conclusions: Depressive symptoms are prevalent among adults with CF and are associated with poorer HRQoL even after controlling for lung function. These results suggest that screening for and treating depression is important and may potentially improve HRQoL among patients with CF.

Key Words: adults • cystic fibrosis • depression • health-related quality of life • lung function • psychosocial • pulmonary function test

Advances in the diagnosis and treatment of cystic fibrosis (CF) have led to a substantial increase in survival rates with a growing percentage of individuals with CF surviving into adulthood. In 2005, the median survival age for individuals with CF in the United States was 36.5 years, and > 40% of patients were ≥ 18 years.1 With increased survival, more research and clinical attention is turning toward evaluating and improving the health-related quality of life (HRQoL) of adults with CF. Little is known about the factors that contribute to HRQoL in CF patients. Indicators of disease severity (eg, lung function, body mass index, exercise performance, and pulmonary exacerbations) are only modestly related to HRQoL scores,23456 indicating that additional factors are important. Staab et al4 found that treatment burden (ie, the number of hours per day spent in therapy), health perceptions, and coping style explained a significant amount of variance in HRQoL beyond disease severity. However, little is known about the role other factors such as depression may play.

Previous studies have suggested that depressive symptoms are common in adults with CF. One study7 found that 46% of adults screened positive for depressive symptoms, with 12% having symptoms in the moderate-to-severe range. Another study8 found that while mean scores were within normal limits, 12% of adults with CF scored outside the normal range on a battery of depression and anxiety measures. Although there is no standardized definition for depression, in the 2005 CF patient registry, 16% of adults were noted to have depressive symptoms.1 The extent to which depressive symptoms contribute to HRQoL in adults with CF is not known. A substantial body of literature across other chronic illnesses, including asthma, COPD, congestive heart failure, epilepsy, and diabetes, has suggested that depressive symptoms are associated with HRQoL91011121314 and even predict HRQoL,1516 independent of disease severity. Treating depression can improve depressive symptoms, health-related functioning, and HRQoL.17 Thus, the objective of this study was to evaluate the relationships among disease severity (ie, lung function), depressive symptoms, and HRQoL in adults with CF. We hypothesized that the presence of depressive symptoms would be associated with significantly worse HRQoL even after controlling for disease severity.

Materials and Methods

This was a cross-sectional study that was conducted from April 2002 to November 2003. Adults ≥ 18 years of age were eligible to be included if they had a confirmed diagnosis of CF, had been seen in the clinic previously, and were scheduled for an outpatient appointment. A recruiter telephoned the patient, explained the study, assessed eligibility, and obtained verbal consent to mail the study materials. Participants completed the questionnaires at home and mailed back the consent form and questionnaires. If the questionnaire was not returned, the recruiter telephoned to remind them to do so and to answer questions. If the questionnaires were still not returned, study materials were mailed once more, with no additional phone contact. Participants were compensated for their participation with a payment of $20. The study protocol was approved by the Western Institutional Review Board.

Lung function results (ie, FEV1 percent predicted) obtained closest to the date of survey completion were abstracted from the participants’ medical record. Forty-five percent of participants had undergone a lung function test within ± 4 weeks of completing the survey, and almost all participants (97%) had undergone the test within ± 6 months. An FEV1 of ≥ 70% predicted indicated mild illness, an FEV1 of ≥ 40 to 69% predicted indicated moderate illness, and an FEV1 of < 40% indicated severe illness.1 FEV1 percent predicted has previously been shown1819 to be a predictor of 2-year and 5-year survival.

Depressive symptoms were assessed using the Beck Depression Inventory (BDI).20 The BDI is one of the most widely accepted clinical instruments for assessing severity of depression. Scores can range from 0 to 63, with higher scores indicating greater depressive symptomatology. Scores of 0 to 9 are considered to be asymptomatic, with scores of 10 to 18 and 19+, respectively, indicating mild and moderate-to-severe levels of depressive symptoms. Participants with scores in the moderate-to-severe range, suggesting clinically significant levels of depressive symptoms, were called by the first author and were offered assistance to obtain further assessment and treatment.

HRQoL was assessed using the Cystic Fibrosis Questionnaire (CFQ) teen/adult version.21 The measure consists of the following 12 subscales: physical (eg, ability to perform physical activities); role (eg, work/school limitations); vitality (eg, tired/energetic); emotional state (eg, sad/lonely); social/marginalization (eg, "have to stay home more than wanted"); body image (eg, perception of physical appearance); eating disturbance (eg, "force self to eat"); treatment burden (eg, ease of incorporating regimen into life); perception of health (eg, "lead a normal life"); weight ("trouble gaining weight"); respiratory (eg, wheezing/coughing); and digestion (eg, gas/diarrhea). Scores range from 0 to 100, with higher scores indicating better HRQoL. All subscales have been shown to have adequate internal consistency and test-retest reliability, and have demonstrated good convergent and predictive validity.621 The Cronbach {alpha} for the subscales ranged from 0.62 to 0.96 for this sample.

Descriptive statistics employed means (SD), medians, and proportions. All CFQ subscales were negatively skewed with a high proportion of participants scoring at the upper limit. Because no transformation normalized the distributions, nonparametric statistics were used. Spearman rho was used to test the associations among depressive symptoms, lung function, and HRQoL. To examine whether disease severity was an effect modifier of the relationship between depressive symptoms and HRQoL, we stratified by FEV1 percent predicted severity categories. Similarly, we stratified by the presence or absence of depressive symptoms to examine whether it modified the relationship between lung function and HRQoL. To further test for the effect modification of lung function and depressive symptoms on HRQoL, we divided participants into the following four groups: group 1, good lung function (FEV1, ≥ 70% predicted)/low depression (BDI score, < 10); group 2, good lung function/high depression (BDI score, ≥ 10); group 3, poor lung function (FEV1, < 70% predicted)/low depression; and group 4, poor lung function/high depression. The Kruskal-Wallis test with Bonferroni correction (due to multiple comparisons) was employed for the initial bivariate analyses. Post hoc exploratory analyses were conducted to examine group differences using the Mann-Whitney U test. Results were reanalyzed using different cut points for lung function (median score) and other published recommendations for BDI cut points202223 as well as removing somatic complaint items.24 The results were the same regardless of the cut point used. Computations were performed using a statistical software package (SPSS, version 14.0; SPSS; Chicago, IL).25

Results

One hundred thirty-three patients met the study eligibility requirements. Of these, 109 patients (82%) verbally consented, 11 (8%) refused consent, 7 (5%) were unable to be contacted, and 6 (5%) died before being contacted. Of the 109 participants, 80 (73%) returned the survey and 1 (1%) died before completing the survey. Two participants who returned completed surveys failed to return a consent form, one person had missing lung function data, and one person had missing depression data; they were all excluded from the analysis. A total of 76 questionnaires were available for the final analysis, which represents 57% of all eligible participants (76 of 133 were eligible).

Participants
Demographic characteristics are presented in Table 1 . FEV1 ranged from 21% to 116% predicted, with a mean of 62.8% predicted (SD, 24.6% predicted); the majority of participants (62%) had an FEV1 of < 70% predicted. Eighty-seven percent of participants were pancreatic insufficient, and CF-related diabetes was diagnosed in 26%. No participant had undergone a lung transplant. Based on chart review, 12 participants (15.8%) were currently being treated for depression; 11 participants were receiving therapy with antidepressants, and 1 participant was receiving counseling.


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  		Table 1. Patient Characteristics*

 
Depressive Symptoms
Thirty percent of participants screened positive for clinically significant levels of depressive symptoms (ie, BDI score ≥ 10); 15 participants (19.7%) scored in the mild range (BDI score, 10 to 18), while 8 participants (10.5%) had moderate-to-severe levels of depressive symptoms (BDI score ≥ 19). Four of the 12 participants being treated for depression had BDI scores < 10; 1 person receiving treatment had a BDI score ≥ 19. Depressive symptoms and FEV1 percent predicted were inversely correlated (rho = –0.25; p < 0.05), with higher depressive symptoms being associated with poorer lung function. Participants with poor lung function (ie, FEV1, < 70% predicted) had three times the odds (95% confidence interval, 1.0 to 9.2) of a positive screen for depressive symptoms (BDI score ≥ 10) than those with better lung function. (38% vs 17%, respectively; p = 0.05).

FEV1 Percent Predicted, Depressive Symptoms, and HRQoL
All CFQ subscales were inversely correlated with depression scores (rho = –0.23 to –0.74). That is, higher depressive symptoms were associated with poorer HRQoL (Table 2 ). After stratifying by FEV1 percent predicted, the association between depressive symptoms and CFQ subscales was maintained regardless of lung function status. Similarly, all CFQ subscales were positively correlated with FEV1 percent predicted scores (rho = 0.32 to 0.57), except for the emotional state and digestion subscales, which were not significantly correlated. That is, better lung function was associated with better HRQoL. Interestingly, when participants were stratified by the presence or absence of depressive symptoms, the association between HRQoL and lung function was unchanged for patients with high levels of depressive symptoms. For participants without depressive symptoms, only the physical, health perceptions, and weight CFQ subscales were significantly correlated with lung function, as is shown in Table 2.


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  		Table 2. Spearman rho Correlations Among HRQoL Scores, Lung Function, and Depressive Symptoms (n = 76)

 
To further evaluate the relationship between lung function, depressive symptoms, and HRQoL, we conducted exploratory analyses by dividing participants into the following four groups: group 1, good lung function (FEV1 ≥ 70% predicted)/low depression (BDI score < 10; n = 24); group 2, good lung function/high depression (n = 5); group 3, poor lung function/low depression (n = 29); and group 4, poor lung function/high depression (n = 18). The Kruskal-Wallis test with Bonferroni correction (p = 0.05; per 12 comparisons, p = 0.004) showed statistically significant group differences for all but the weight subscale. We were specifically interested in the post hoc comparison of groups 1 vs 3, 1 vs 4, and 3 vs 4. Group 2 was not included in the post hoc analyses because it included only five participants. The physical subscale was the only statistically significant difference between groups 1 and 3 (Mann-Whitney U test = 233.0; p < 0.05) [Fig 1 ]). Thus, in the absence of depressive symptoms, poor lung function had relatively little association with HRQoL compared with good lung function, except in physical functioning. Surprisingly, there was no statistical difference in scores on the respiratory subscale (Mann-Whitney U test = 276.0; p = 0.20). In contrast, participants with both poor lung function and depressive symptoms (group 4) had significantly poorer HRQoL on all subscales relative to the participants in group 1 (p < 0.01). Similar results were found when comparing participants with poor lung function with and without depressive symptoms (groups 3 and 4). Those participants with depressive symptoms had statistically significantly lower HRQoL scores on all CFQ subscales than those participants without depressive symptoms (p < 0.01) [Fig 1].


Figure 1
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  		Figure 1. Associations among lung function, depression, and HRQoL (median scores). White column = group 1; gray column = group 2; dotted column = group 3; black column = group 4.* = n = 23 for good lung function/low depressive symptoms; n = 5 for good lung function/high depressive symptoms; n = 25 for poor lung function/low depressive symptoms; and n = 13 for poor lung function/high depressive symptoms due to missing data. {dagger} = Comparison of group 1 to group 4, p < 0.05. {ddagger} = Comparison of group 3 to group 4, p < 0.05. § = Comparison of group 1 to group 3, p < 0.05.

 
Discussion

Consistent with previous studies,178 our study found that depressive symptoms are common among adults with CF, with 30% of participants exhibiting signs of depressive symptoms and 11% of participants screening positive for moderate-to-severe levels of depression. Only 13% of those participants who screened positively for moderate-to-severe levels of depressive symptoms were currently receiving treatment, suggesting that depression may be underdiagnosed and untreated in this population. Although individuals with poor lung function were three times as likely to exhibit depressive symptoms, overall, most of the persons in our sample who were in poor physical health were not depressed.

Fewer depressive symptoms and higher lung function were associated with better HRQoL, with the association between depressive symptoms and HRQoL remaining even after controlling for disease severity. Similarly, in the absence of depressive symptoms, those with good lung function reported better physical HRQoL than those with poor lung function; however, this relationship was not as strong for the other CFQ subscales. In contrast, participants with both depressive symptoms and poor lung function reported significantly worse HRQoL than participants without depressive symptoms, regardless of their lung function status. These results suggest that poor lung function alone does not necessarily lead to poorer HRQoL. Within individuals with poor lung function, however, the presence of depressive symptoms is associated with a dramatically lower HRQoL across all domains, suggesting a synergistic effect between depressive symptoms and lung function.

Our findings of poorer HRQoL in depressed participants have been reported in cross-sectional and prospective studies of patients with other chronic illnesses.91213142627 Although as yet there are no CF-specific data, in patients with other chronic illnesses, depression is a risk factor for poor adherence to therapy,2829 increased mortality,30313233 increased health-care utilization,263435 and increased health-care costs.27 While the assessment and treatment of depression is in itself important, depressive symptoms appear to serve as an important prognostic indicator and therefore should be considered an important component of medical care. Research is needed to evaluate whether depression is also associated with these poorer health outcomes in persons with CF.

Pharmacotherapy and psychotherapy are effective treatments, particular when used in combination, for treating depression in the general population.363738 Further, depression therapies are safe and effective in reducing depressive symptoms in chronically ill patients.394041 Some studies42 have found that treating depression in patients with chronic illnesses results in reduced morbidity and mortality, but others39 have not shown that treating depression influences health outcomes. However, nonresponse to depression treatment may be a risk factor for mortality.43 Studies are needed to evaluate the effect of treating depressive symptoms in CF patients. Some side effects of pharmacotherapy may be particularly contraindicated or beneficial for patients with CF, such as the loss of appetite and anorexia or weight gain that can accompany the use of some antidepressants.44 Until CF-specific data are available, decisions about the type of depression therapy should take into consideration potential drug interactions, tolerability of therapy, and patient preferences.

Approximately 85% of patients with CF in the United States are treated at centers accredited by the Cystic Fibrosis Foundation. Medical data from these patients are included in the national Cystic Fibrosis Foundation Patient Registry,1 which includes a single check-box variable to indicate the presence or absence of depression without providing a standardized definition. To date, there has been no guidance provided to centers regarding whether, when, or how to assess for depression or which member of the health-care team is responsible for making the diagnosis, and this has resulted in great variability across CF centers in the proportion of patients classified as being depressed. This study indicates the need to systematically and effectively screen for depression, since it would increase the identification of patients who may benefit from treatment. There are several brief, validated depression screening measures (eg, BDI,2045 Centers for Epidemiologic Studies Depression Scale,46 and the Hospital Anxiety and Depression Scale47) that can be integrated into standard practice. Recently, an international effort has been coordinated through North American CF and European CF conferences to increase depression screening by developing a standardized assessment protocol, using the Hospital Anxiety and Depression Scale, with the results entered into the patient registry. Together, these data will enhance our understanding of not only the prevalence of depressive symptoms, but also the influence of depression on CF morbidity and mortality.

Our participants had mean HRQoL scores that were similar to those found in other studies using the CFQ.48 Similarly, correlations between FEV1 percent predicted scores and CFQ subscales were of comparable or larger magnitude than those found in previous CF research,6 suggesting that our sample is reasonably representative of adults with CF. However, there are several limitations to this study. Data on lung function obtained from medical charts differed from the date of survey completion by > 1 month for 55% of the sample. Thus, the stronger relationship between depression and HRQoL could be due to the temporal relationship between the measures. To address this concern, all analyses were rerun stratifying for those persons who had undergone pulmonary function testing within 4 weeks of completing the survey or > 4 weeks after completing the survey. Both groups showed similar patterns of results (data not shown), suggesting that the timing of the assessments was not a significant confounder of our results. Nevertheless, a concurrent assessment of all variables of interest is needed to fully address these concerns.

Our participants represented 57% of eligible patients from a single CF center. We were unable to assess whether nonparticipants differed from participants in terms of the variables of interest. Because study attrition is higher among depressed patients,4950 our prevalence estimates for depression may be conservative. The cross-sectional nature of this study limits our conclusions; the assessment of psychosocial factors over time would allow inferences about the causal relationships among lung function, depression, and HRQoL. For example, does a decrease in lung function lead to increased depression or does depression precede a loss of lung function and HRQoL? Additionally, although the BDI is one of the most widely used and rigorously validated methods of assessing depressive symptoms in other illnesses including diabetes22 and HIV,23 its use has not been validated in a CF population. Thus, the use of conventional cut points may result in some misclassification of depression. Similarly, some researchers24 have suggested that somatic items be excluded from the measure for more reliable results in chronic illness patients. We analyzed our data using multiple cut points and without the somatic items, and found equivalent results. We chose to use a BDI score ≥ 10 because scores < 10 are indicative of no or minimal depression. Prior research in patients with other chronic illnesses has suggested that even minimal symptoms of depression in absence of a formal diagnosis may have prognostic value,51 and our data suggest that this may be true for adults with CF. Research in persons with CF is needed to confirm the validity of the cut points in this population. Moreover, we did not determine which participants qualified for a diagnosis of major depression; this is an important next step. Finally, we only measured one marker of CF disease severity; additional studies incorporating other measures (eg, number of exacerbations and nutritional status) are needed.

Our results suggest that depressive symptoms are prevalent among adults with CF and are significantly associated with impairments in HRQoL, even after controlling for disease severity. Our data are consistent with the growing body of studies in the literature that have suggested that depression is a significant risk factor for poor health outcomes among individuals with chronic illnesses. Because depression is treatable, our results suggest that periodic screening is appropriate and may potentially improve the HRQoL for persons with CF.

Footnotes

Abbreviations: BDI = Beck Depression Inventory; CF = cystic fibrosis; CFQ = Cystic Fibrosis Questionnaire; HRQoL = health-related quality of life

This research was supported by National Institute of Diabetes and Digestive and Kidney Disease grant 61135 and National Heart, Lung, and Blood Institute grant 63333.

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Received for publication October 11, 2006. Accepted for publication March 19, 2007.

References

  1. . Cystic Fibrosis Foundation. (2005) Patient registry: 2005 annual report. Cystic Fibrosis Foundation. Bethesda, MD:
  2. Britto, MT, Kotagal, UR, Hornung, RW, et al Impact of recent pulmonary exacerbations on quality of life in patients with cystic fibrosis. Chest 2002;121,64-72[Abstract/Free Full Text]
  3. Gee, L, Abbott, J, Conway, SP, et al Quality of life in cystic fibrosis: the impact of gender, general health perceptions and disease severity. J Cyst Fibros 2003;2,206-213[Medline]
  4. Staab, D, Wenninger, K, Gebert, N, et al Quality of life in patients with cystic fibrosis and their parents: what is important besides disease severity? Thorax 1998;53,727-731[Abstract/Free Full Text]
  5. Orenstein, DM, Nixon, PA, Ross, EA, et al The quality of well-being in cystic fibrosis. Chest 1989;95,344-347[Abstract/Free Full Text]
  6. Quittner, AL, Buu, A, Messer, MA, et al Development and validation of the cystic fibrosis questionnaire in the united states: a health-related quality-of-life measure for cystic fibrosis. Chest 2005;128,2347-2354[Abstract/Free Full Text]
  7. Burker, EJ, Sedway, J, Carone, S Psychological and educational factors: better predictors of work status than FEV1 in adults with cystic fibrosis. Pediatr Pulmonol 2004;38,413-418[CrossRef][ISI][Medline]
  8. Anderson, DL, Flume, PA, Hardy, KK Psychological functioning of adults with cystic fibrosis. Chest 2001;119,1079-1084[Abstract/Free Full Text]
  9. Lavoie, KL, Bacon, SL, Barone, S, et al What is worse for asthma control and quality of life: depressive disorders, anxiety disorders, or both? Chest 2006;130,1039-1047[Abstract/Free Full Text]
  10. Johnson, EK, Jones, JE, Seidenberg, M, et al The relative impact of anxiety, depression, and clinical seizure features on health-related quality of life in epilepsy. Epilepsia 2004;45,544-550[CrossRef][ISI][Medline]
  11. Goldney, RD, Phillips, PJ, Fisher, LJ, et al Diabetes, depression, and quality of life: a population study. Diabetes Care 2004;27,1066-1070[Abstract/Free Full Text]
  12. Carels, RA The association between disease severity, functional status, depression and daily quality of life in congestive heart failure patients. Qual Life Res 2004;13,63-72[CrossRef][ISI][Medline]
  13. Hajiro, T, Nishimura, K, Tsukino, M, et al Comparison of discriminative properties among disease-specific questionnaires for measuring health-related quality of life in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1998;157,785-790[Abstract/Free Full Text]
  14. Cully, JA, Graham, DP, Stanley, MA, et al Quality of life in patients with chronic obstructive pulmonary disease and comorbid anxiety or depression. Psychosomatics 2006;47,312-319[Abstract/Free Full Text]
  15. Lane, D, Carroll, D, Ring, C, et al Effects of depression and anxiety on mortality and quality-of-life 4 months after myocardial infarction. J Psychosom Res 2000;49,229-238[CrossRef][ISI][Medline]
  16. Lane, D, Carroll, D, Ring, C, et al Mortality and quality of life 12 months after myocardial infarction: effects of depression and anxiety. Psychosom Med 2001;63,221-230[Abstract/Free Full Text]
  17. Jackson, JL, DeZee, K, Berbano, E Can treating depression improve disease outcomes? Ann Intern Med 2004;140,1054-1056[Free Full Text]
  18. Matouk, E, Ghezzo, RH, Gruber, J, et al Internal consistency reliability and predictive validity of a modified N. Huang clinical scoring system in adult cystic fibrosis patients. Eur Respir J 1997;10,2004-2013[Abstract]
  19. Liou, TG, Adler, FR, FitzSimmons, SC, et al Predictive 5-year survivorship model of cystic fibrosis. Am J Epidemiol 2001;153,345-352[Abstract/Free Full Text]
  20. Beck, AT, Steer, RA, Barbin, MG Psychometric properties of the Beck Depression Inventory: twenty-five years of evaluation. Clin Psychol Rev 1988;8,77-100[CrossRef][ISI]
  21. Quittner, AL, Sweeny, S, Watrous, M, et al Translation and linguistic validation of a disease-specific quality of life measure for cystic fibrosis. J Pediatr Psychol 2000;25,403-414[Abstract/Free Full Text]
  22. Lustman, PJ, Clouse, RE, Griffith, LS, et al Screening for depression in diabetes using the Beck Depression Inventory. Psychosom Med 1997;59,24-31[Abstract/Free Full Text]
  23. Savard, J, Laberge, B, Gauthier, JG, et al Screening clinical depression in HIV-seropositive patients using the Hospital Anxiety and Depression Scale. AIDS Behav 1999;3,167-175[CrossRef]
  24. Cavanaugh, S, Clark, DC, Gibbons, RD Diagnosing depression in the hospitalized medically ill. Psychosomatics 1983;24,809-815[Abstract/Free Full Text]
  25. SPSS, Inc.. Release 14.0.0: SPSS for Windows 2005 SPSS Inc. Chicago, IL:
  26. Eisner, MD, Katz, PP, Lactao, G, et al Impact of depressive symptoms on adult asthma outcomes. Ann Allergy Asthma Immunol 2005;94,566-574[ISI][Medline]
  27. Creed, F, Morgan, R, Fiddler, M, et al Depression and anxiety impair health-related quality of life and are associated with increased costs in general medical inpatients. Psychosomatics 2002;43,302-309[Abstract/Free Full Text]
  28. DiMatteo, MR, Lepper, HS, Croghan, TW Depression is a risk factor for noncompliance with medical treatment: meta-analysis of the effects of anxiety and depression on patient adherence. Arch Intern Med 2000;160,2101-2107[Abstract/Free Full Text]
  29. Smith, A, Krishnan, JA, Bilderback, A, et al Depressive symptoms and adherence to asthma therapy after hospital discharge. Chest 2006;130,1034-1038[Abstract/Free Full Text]
  30. Almagro, P, Calbo, E, Ochoa de Echaguen,, et al Mortality after hospitalization for COPD. Chest 2002;121,1441-1448[Abstract/Free Full Text]
  31. Cook, JA, Grey, D, Burke, J, et al Depressive symptoms and AIDS-related mortality among a multisite cohort of HIV-positive women. Am J Public Health 2004;94,1133-1140[Abstract/Free Full Text]
  32. Egede, LE, Nietert, PJ, Zheng, D Depression and all-cause and coronary heart disease mortality among adults with and without diabetes. Diabetes Care 2005;28,1339-1345[Abstract/Free Full Text]
  33. Barth, J, Schumacher, M, Herrmann-Lingen, C Depression as a risk factor for mortality in patients with coronary heart disease: a meta-analysis. Psychosom Med 2004;66,802-813[Abstract/Free Full Text]
  34. Sullivan, MD, Levy, WC, Crane, BA, et al Usefulness of depression to predict time to combined end point of transplant or death for outpatients with advanced heart failure. Am J Cardiol 2004;94,1577-1580[CrossRef][ISI][Medline]
  35. Himelhoch, S, Weller, WE, Wu, AW, et al Chronic medical illness, depression, and use of acute medical services among Medicare beneficiaries. Med Care 2004;42,512-521[CrossRef][ISI][Medline]
  36. Arroll, B, Macgillivray, S, Ogston, S, et al Efficacy and tolerability of tricyclic antidepressants and SSRIs compared with placebo for treatment of depression in primary care: a meta-analysis. Ann Fam Med 2005;3,449-456[Abstract/Free Full Text]
  37. Pampallona, S, Bollini, P, Tibaldi, G, et al Combined pharmacotherapy and psychological treatment for depression: a systematic review. Arch Gen Psychiatry 2004;61,714-719[Abstract/Free Full Text]
  38. Arnow, BA, Constantino, MJ Effectiveness of psychotherapy and combination treatment for chronic depression. J Clin Psychol 2003;59,893-905[CrossRef][ISI][Medline]
  39. Berkman, LF, Blumenthal, J, Burg, M, et al Effects of treating depression and low perceived social support on clinical events after myocardial infarction: the Enhancing Recovery in Coronary Heart Disease Patients (ENRICHD) randomized trial. JAMA 2003;289,3106-3116[Abstract/Free Full Text]
  40. Lustman, PJ, Griffith, LS, Freedland, KE, et al Cognitive behavior therapy for depression in type 2 diabetes mellitus: a randomized, controlled trial. Ann Intern Med 1998;129,613-621[Abstract/Free Full Text]
  41. Krishnan, KR Treatment of depression in the medically ill. J Clin Psychopharmacol 2005;25(suppl),S14-S18[CrossRef][ISI][Medline]
  42. Taylor, CB, Youngblood, ME, Catellier, D, et al Effects of antidepressant medication on morbidity and mortality in depressed patients after myocardial infarction. Arch Gen Psychiatry 2005;62,792-798[Abstract/Free Full Text]
  43. Carney, RM, Blumenthal, JA, Freedland, KE, et al Depression and late mortality after myocardial infarction in the enhancing recovery in coronary heart disease (ENRICHD) study. Psychosom Med 2004;66,466-474[Abstract/Free Full Text]
  44. Cheer, SM, Goa, KL Fluoxetine: a review of its therapeutic potential in the treatment of depression associated with physical illness. Drugs 2001;61,81-110[CrossRef][ISI][Medline]
  45. Beck, AT, Steer, RA, Brown, GK Manual for the Beck depression inventory II. 1996 Psychological Corporation. San Antonio, TX:
  46. Radloff, LS The CES-D scale: a self-report depression scale for research in the general population. Appl Psychol Meas 1977;1,385-401[CrossRef]
  47. Zigmond, AS, Snaith, RP The hospital anxiety and depression scale. Acta Psychiatr Scand 1983;67,361-370[ISI][Medline]
  48. Elkins, MR, Robinson, M, Rose, BR, et al A controlled trial of long-term inhaled hypertonic saline in patients with cystic fibrosis. N Engl J Med 2006;354,229-240[Abstract/Free Full Text]
  49. Clark, MM, Niaura, R, King, TK, et al Depression, smoking, activity level, and health status: pretreatment predictors of attrition in obesity treatment. Addict Behav 1996;21,509-513[CrossRef][ISI][Medline]
  50. Bech, P, Lucas, R, Amir, M, et al Association between clinically depressed subgroups, type of treatment and patient retention in the LIDO Study. Psychol Med 2003;33,1051-1059[CrossRef][ISI][Medline]
  51. Bush, DE, Ziegelstein, RC, Tayback, M, et al Even minimal symptoms of depression increase mortality risk after acute myocardial infarction. Am J Cardiol 2001;88,337-341[CrossRef][ISI][Medline]




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