Response to "Does Sleep Play a Role in the Relationship Among Depression, Anxiety, and Mortality in Lung Transplanted Patients?"

A Scoping Review of the Literature on Sleep Quality in Adult Lung Transplant Recipients

Introduction: Lung transplant recipients face challenging postoperative complications and are at risk for poor sleep quality. Sleep quality, as a complex clinical phenomenon, has multiple subjective and objective connotations. Measures and definitions of sleep quality are not standardized. Objective: A scoping review methodology was used to systematically map the relevant literature, provide an overview of available sleep quality measures, and to identify knowledge gaps. Methods: A systematic search of published and gray literature enabled knowledge synthesis of the last 10 years of evidence documenting sleep quality in lung transplant recipients. The search revealed 246 articles with only 12 sources meeting the eligibility criteria. Results: Sources varied in terms of definitions and measures of sleep quality. Subjective, objective, or a combination of both measures were used across the relevant literature with findings confirming that poor sleep quality was common in lung transplant recipients. Significant associations with poor sleep quality included younger age, female gender, exposure to tacrolimus, anxiety, and depression. Discussion: Systematic literature assessing sleep quality in lung transplant recipients is sparse and lacks conceptual and operational definitions. Future research can focus on designing prospective observational studies. Subjective and objective measures for sleep quality need to be validated in lung transplant recipients. Further rigorous research is needed to standardize measures of sleep quality and to further examine potential risk factors that affect sleep after lung transplantation.

Sleep quality, depressive symptoms, and transplant outcomes: Follow-up analyses from the ADAPT prospective pilot study

BACKGROUND

Previous studies suggested that depressive symptoms and sleep quality may be important for long-term clinical outcomes following cardiothoracic transplant. Few studies, however, have systematically examined objective markers of these behavioral factors among ambulatory transplant recipients, or their association with clinical outcomes.

METHODS

We examined sleep quality and depressive symptoms with subsequent clinical outcomes (hospitalizations and death) in a sample of 66 lung or heart transplant recipients using a single-center, prospective cohort study. Recipients were assessed at approximately 6 months post-transplant and completed one week of actigraphy assessment to examine sleep quality and self-report measures of mood (Centers for Epidemiologic Studies of Depression [CESD]). Recipients were followed for clinical outcomes.

RESULTS

At 6-months following transplantation, recipients spent the majority of daytime activity at a sedentary level (61% of daily activity [SD = 10]) and elevated depressive symptoms were common (subclinical = 17%, mild = 12%, or moderate = 8%). Over a median follow-up of 4.5 years (IQR = 0.9, 5.1), 51 participants (77%) had at least one unplanned hospitalization and 11 (17%) participants died. In addition, sleep efficiency measurements suggested that a subset of participants exhibited suboptimal sleep (mean efficiency = 87% [SD = 7]). Poorer sleep quality, indexed by lower sleep efficiency and greater sleep fragmentation, was associated with greater depressive symptoms (r's = 0.37-0.50, P < .01). Better sleep quality at 6-months (HR = 0.75 [0.60, 0.95], P = .015), including sleep efficiency (HR = 0.74 [0.56, 0.99], P = .041) and sleep fragmentation (HR = 0.71 [0.53, 0.95], P = .020) were associated with lower risk of hospitalization or death. Compared with individuals without elevated depressive symptoms or sleep difficulties, individuals with either factor (HR = 1.72 [1.05, 2.81], P = .031) or both factors (HR = 2.37 [1.35, 4.18], P = .003) exhibited greater risk of clinical events in adjusted analyses.

CONCLUSIONS

Sleep quality is associated with depressive symptoms among cardiothoracic transplant recipients and enhances the prognostic association between biobehavioral risk factors and clinical outcomes.

Depressive Symptoms, Exercise Capacity, and Clinical Outcomes After Lung Transplantation

OBJECTIVE

Depressive symptoms are common among lung transplant recipients and have been associated with worse clinical outcomes. However, few studies have examined the association between depressive symptoms assessed at multiple time points or behavioral mechanisms by which posttransplant depressive symptoms may confer greater clinical risk. We therefore examined the associations between depressive symptoms, exercise capacity, chronic lung allograft dysfunction (CLAD), and mortality prospectively in a large sample of lung transplant recipients.

METHODS

Between July 2009 and February 2016, 251 lung transplant recipients were assessed before transplantation and again approximately 3 weeks and 3 months after transplant. Depressive symptoms were assessed using the Centers for Epidemiologic Studies of Depression scale. Functional exercise capacity was assessed using the 6-minute walk test. Cox proportional hazards models were used to examine the associations between depressive symptoms, exercise capacity, CLAD, and mortality.

RESULTS

During a median (range) follow-up of 4.5 (0.1 to 6.3) years, 53 participants (21%) died. Greater depressive symptoms (hazard ratio [HR] = 1.39 [95% CI = 1.05 to 1.84], p = .021) and poorer exercise capacity (HR = 0.58 [95% CI = 0.38 to 0.90], p = .021) assessed 3 months after transplant were both independently associated with mortality. Although greater depressive symptoms were associated with lower exercise capacity (β = -0.14, p = .039), exercise capacity did not mediate the association between depressive symptoms and mortality. In secondary analyses, depressive symptoms were independently predictive of CLAD (HR = 1.29 [95% CI = 1.01 to 1.65], p = .045) and the composite outcome of CLAD and mortality in a clustered event model (HR = 1.30 [1.09 to 1.56], p = .005).

CONCLUSIONS

Depressive symptoms are associated with mortality and CLAD after lung transplantation, independent of exercise capacity.

Depressive symptoms and early mortality following lung transplantation: A pilot study

BACKGROUND

Impaired psychological function is common among lung transplant candidates and may affect clinical outcomes following transplantation. Although numerous studies have examined the relationship between pretransplant depression, quality of life (QoL), and post-transplant outcomes, few have examined the relationship between depression and QoL shortly following transplantation and subsequent clinical outcomes. We therefore examined the association between depression, QoL, and short-term mortality in a consecutive series of lung transplant recipients.

METHODS

Depression (Patient Health Questionnaire-9; Hospital Anxiety and Depression Scale; Centers for Epidemiologic Studies Depression Scale) and QoL (UCSD Shortness of Breath Questionnaire; Pulmonary Quality of Life Scale) were assessed prior to transplantation (median 0.9 months [IQR=1.6]) and again approximately 2 weeks following transplantation (median=0.5 months [IQR=0.5]), in a series of 66 patients transplanted between March 2013 and April 2014. The association between psychiatric diagnoses from participants' comprehensive pretransplant assessment and mortality also was examined. Cox proportional hazards models were used to examine the association between depression, QoL, and mortality.

RESULTS

During a median follow-up of 2.8 years (range 0.4-3.3), 21 patients died (32%). Greater depressive symptoms assessed shortly after transplant were associated with subsequent mortality (HR=2.17 [1.01, 4.67], P=.048), and this relationship persisted after controlling for primary graft dysfunction, duration of transplant hospitalization, and gender. In contrast, neither pretransplant depression, history of depression, nor QoL was associated with mortality.

CONCLUSIONS

Greater post-transplant depressive symptoms are independently associated with mortality among lung transplant recipients.