Serum Albumin and Depression in End-Stage Renal Disease

Ronald Friend,l Lena Hatchett,l Nand K. Wadhwa,2 Heesuck Suh2

The purpose of our study was to determine whether albumin influenced patients' depression or whether depression influenced patients' albumin.

Patients from a tertiary care university medical hospital were assessed for both serum albumin and depression [Beck Depression Inventory (BDI)J at two time points separated by 6 months. Data were collectedfor 72 patients (43 male, 29 female,. mean age 54 years). The sample consisted of 32 hemodialysis and 40 peritoneal dialysis patients. The outcome measures were changes in depression and albumin over time.

Regression analysis indicated that all three Time I measures of BDI, BDICOG (BDI cognitive), and BDISOM (BDI somatic) significantly predicted decreases in albuminfrom Time I to Time 2 ({3 = -0.22, p < 0.002; {3 = -0.17, p < 0.015; {3 = -0.23, p < 0.002, respectively). However; Time 1 measures of albumin did not predict changes in BDI, BDICOG, or BDISOM ({3 = -0.04, p < 0.738; {3 = -0.08, p < 0.375; {3 =-0.07, p < 0..618, respectively). Thusdepression at Time 1 predicted decreases in albumin .from Time 1 to Time 2. The reverse effect that albumin influences depression from Time 1 to Time 2 was not found.

In conclusion, this study suggests that depression influences the nutritional status indicated by albumin levels. Thus poor nutritional status may mediate the relation between depression and mortality in endstage renal disease (ESRD).

Key words

Albumin, depression, dialysis, end-stage renal disease

From:

Department of Psychologyl and Department of Medicine,2 State University of New York at Stony Brook, New York, U.S.A.

Introduction

Serum albumin levels are used to assess the nutritional status of end-stage renal disease (ESRD) patients. Research with large study samples has shown that low albumin concentrations are a reliable predictor of mortality in ESRD ( 1,2). Consequently, it is important to determine the factors associated with low albumin levels. One such factor may be depression. There is some indication that depression (3-5), or psychiatric illness in general ( 6), is related to mortality in ESRD patients, although some studies have not observed such a relation (7-9). One theory, depicted in Model A (see Figure I), is that depression leads to lower levels of albumin, which in turn lead to higher mortality rates.

There are, however, two alternative hypotheses. It is also possible that poor nutritional levels (resulting from loss of appetite) lead to depression, which in turn results in higher mortalities. In fact, poor appetite is assessed by one of the most widely used measurements of depression, the Beck Depression Inventory (BDI). As depicted in Model B (see Figure I ), this hypothesis suggests that poor albumin levels are an indicator of poor nutritional status; poor nutritional status leads to depression, which in turn results in higher mortalities.

An alternative hypothesis is that disease severity covaries with albumin (10), depression, and mortality, in some combination of one or more of these factors. Therefore, it is necessary to control for disease severity. While this study does not attempt to assess mortality, it does address the possible relationship between depression and albumin, while controlling for disease severity and functional status. First, to our knowledge no study has linked depression and albumin. Second, if such a relation exists, what is the causal sequence?

In the present study, patients are assessed for depression and albumin at two time points separated by 6 months, making it possible to evaluate the causal nexus: does depression at Time I predict changes in albumin between Time I and Time 2 and/or does albumin at Time I predict changes in depression from Time I to Time 2, controlling for disease severity?

Patients and methods
Subjects

All data were collected on 72 ESRD patients (32 hemodialysis and 40 peritoneal dialysis, 43 men and 29 women). The average age was 54 years (range 22 84 years), and the average time on dialysis was 3.5 years. Sixty-four percent of the patients were married, and 83% were white. Albumin and disease severity and depression scores were available for all subjects at Time I and Time 2 with the exception that only depression scores were available at Time 2 for 54 patients. Depression was assessed by two graduate students and disease severity by two nephrologists, who were unaware of the purpose of the study.

Measures

In this prospective study, 72 ESRD patients were assessed for albumin and depression at two time points separated by 6 months.

Depression

The Bill is a widely used scale to assess depression ( II ). Scores were available for 72 patients at Time I and 54 patients at Time 2. For the purposes of this study three scores were generated: the total Bill (BillTOT) score (23 items), the BDI cognitive (BillCOG) subscore ( 15 items), and the Bill somatic (BillSOM) subscore (5 items; changes in appetite, sleep, activity, etc.). The cognitive subscale has been shown to accurately assess depression in ESRD patients by excluding the somatic items, which may also be influenced by ESRD.

Disease severity

Disease severity was assessed by the ESRD Disease Severity Index (10,12) and the Kamofsky Performance Status Scale Index (13). The ESRD Disease Severity Index consists of II items representing disease categories commonly observed in patients with ESRD.

Albumin

Albumin was assessed by averaging three measures of albumin levels at two time points separated by 6 months. These scores were collected concurrently with the assessment of depression.

Results

Hierarchical regressions were used to test whether the data matched Model A or Model B. In order to test Model A, three hierarchical regressions were conducted for each depression measure ( total, cognitive, and somatic). In these hierarchical analyses, albumin at Time I, disease severity, and functional status were entered in the first step as control variables, and one of the three depression measures in the second step to predict albumin at Time 2. They test whether depression predicts changes in albumin levels between Time I and Time 2. Results of all three regressions indicate that BillTOT (/3 = -0.22; p < 0.002), BillCOG (/3 = -0.17;p < 0.015), and BillSOM (/3 = -0.23; p < 0.002) all predicted albumin at Time 2.

In order to test Model B, the reverse hierarchical regressions were conducted. In these analyses, the specific measure of depression was entered with disease severity and functional status in the first step, and Time I albumin in the second step, to predict depression at Time 2. In all cases, the results showed that albumin at Time I did not predict changes in depression for BillTOT (/3 = -0.04, p < 0.738), BillCOG (/3 = -0.08, p < 0.375), or BillSOM (/3 = -O.07,p < 0.618).

In summary, results indicate that depression at Time I predicted changes in albumin across time, but albumin did not predict changes in depression.

Discussion

The results of the present study suggest that the causal relation between albumin and depression is such that depression results in decreased albumin rather than the reverse, that poor nutritional status (low albumin) results in increases in depression. The separation of the Bill into its psychological and somatic components confirms this analysis. The subscale score with the psychological items from the Bill predict changes in albumin as well as the somatic items. This is important, since the somatic items of the BDl, in the case of ESRD, overlap with uremia and may not unambiguously reflect depression in renal patients. Thus the findings on the psychological BDl subscale, together with our controlling for disease severity, underscore that it is depression rather than disease factors that is related to poor nutritional status. Future research is needed to investigate whether albumin moderates or mediates a possible relation between depression and mortality.

One implication of these results is that the relationship between depression and poor nutritional status in ESRD patients should be taken more seriously. ESRD patients can be easily assessed for depression and albumin scores monitored to observe any reduction in nutritional status. If this should be the case, the patients , psychological status may need to be addressed.

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Corresponding author:
Nand K. Wadhwa, MD, Division of Nephrology and Hypertension, HSC, T -15, Room 020, Stony Brook, New York 11794-8152 U.S.A.