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ORIGINAL ARTICLES |
From the Department of Psychology and Behavioral Medicine (G.I., C.O., J.P.L., E.B., N.S.), Department of Psychiatry (G.I., N.S.), Department of Medicine (M.A.F., N.K., N.S.), University of Miami, Coral Gables, Florida.
Address correspondence and reprint requests to Gail Ironson, MD, PhD, Department of Psychology and Behavioral Medicine, University of Miami, PO Box 248185, Coral Gables, FL 33124-2070. E-mail: gironson{at}aol.com
| ABSTRACT |
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Methods: This longitudinal study assessed a multiethnic HIV+ sample (n = 177) of men and women in the midrange of illness (CD4 number between 150 and 500; no previous acquired immunodeficiency syndrome [AIDS]defining symptom) every 6 months for 2 years. Hierarchical linear modeling was used to model change in CD4 and VL controlling for sociodemographics (age, gender, ethnicity, education) and medical variables (baseline CD4/VL, antiretroviral medications at each time point, adherence).
Results: Baseline depression, hopelessness, and education predicted the slope of CD4 and VL. Avoidant coping and life event stress predicted VL change. Cumulative variables produced stronger relationships (depression, avoidant coping, and hopelessness with CD4/VL slope and life events stress with VL slope). High cumulative depression and avoidant coping were associated with approximately twice the rate of decline in CD4 as low scorers and greater relative increases in VL. Social support was not significantly related to CD4 or VL slope.
Conclusions: Psychosocial factors contribute significantly to the variance in HIV disease progression (assessed through CD4 number and VL) in a diverse sample, accounting for adherence and do so in the era of HAART.
Key Words: HIV/AIDS disease progression adherence depression coping stress
Abbreviations: HAART = highly active antiretroviral treatment; VL = viral load; HIV = human immunodeficiency virus; AIDS = acquired immunodeficiency syndrome; PI = protease inhibitor; HLM = hierarchical linear modeling; DR = decline ratio; SES = socioeconomic status; BDI = Beck Depression Inventory; BHS = Beck Hopelessness Scale; N/A = not applicable.
| INTRODUCTION |
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The present longitudinal study expands on the above findings by reporting on a diverse sample of men and women conducted entirely during a period of widespread HAART/PI availability, by examining several psychosocial predictors in addition to depression, and by predicting the change in both CD4 cells and viral load (VL) over time. VL was not available when most of the earlier studies were undertaken. In addition, since some studies suggested that cumulative measurement of psychosocial variables could be important (6,8,13), a comparison of baseline and cumulative measurement of these variables was undertaken. The intent was to determine if the psychosocial variables would predict above both traditional control variables (i.e., age, race, gender, socioeconomic status [SES]), as well as medically important behaviors (i.e., adherence, initial disease status, medications prescribed). This was accomplished using a statistical methodology, hierarchical linear modeling (HLM), that allowed for the control of medication changes at every time point. CD4 cell counts and VL were chosen because of their ability to predict clinical outcomes (21,22).
Adherence to antiretroviral medications prescribed for the treatment of HIV is central to the effective management of the disease (2325). Poorer adherence to antiretroviral medications has been associated with more rapid HIV disease progression as measured by HIV-1 VL or CD4 cell counts (2630) and has been associated with the emergence of viral mutations which can result in medication resistance (23,28,31).
The relationship between medication adherence in HIV and psychosocial factors is well established. Poorer adherence has been related to stressful life events, depression, hopelessness and anxiety, lower social support, lower levels of patient knowledge about HIV, as well as characteristics of the treatment and treatment setting (3236). As medication adherence is of central importance to both HIV disease progression and sensitive to the psychosocial milieu of the patient, its relationship with the psychosocial predictors in this study and its relationship to the disease progression markers were also carefully considered.
| METHODS |
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Design
This study used a longitudinal design where participants were assessed every 6 months for a period of 2 years. The accrual period lasted 2.5 years, and the study period was from 1997 to 2002.
Procedures
At baseline, subjects completed written informed consent, psychosocial questionnaires, a clinical assessment interview, and blood draw for CD4 and VL assay. Follow-up visits, repeated every 6 months, included the questionnaire battery, brief interview, and blood draw. Study procedures, including informed consent, were approved by the institutional review board.
Measures
Demographics and background medical information (see Table 1) were assessed by self-report. Prescribed medications and adherence were assessed through interviewer-administered AIDS Clinical Trials Group (ACTG) Adherence Measure (32). Adherence was calculated as the percentage of missed doses averaged over each assessment time point for which the subject was taking medications. Past drug/alcohol abuse and dependence and psychotic symptoms were assessed using the interviewer administered Structured Clinical Interview Diagnostic-Diagnostic and Statistical Manual-III-R.
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Disease Progression Markers
CD4 lymphocyte count (CD3+CD4+) was determined by whole-blood 4-color direct immunofluorescence using a coulter XL-MCL flow cytometer. VL utilized the Roche Amplicor RT/PCR assay sensitive to 400 copies of plasma RNA.
Psychosocial Measures
Depression was assessed by the Beck Depression Inventory (BDI) (37), a 21-item scale of cognitive, affective, and behavioral symptoms of depression over the past week, which includes subscales for affective and somatic symptoms (38). Hopelessness was measured by the Beck Hopelessness Scale (BHS) (39), a 20-item true/false questionnaire that examines feelings about the future, loss of motivation, and expectations. Coping strategies were assessed using the COPE (40), a 24-item scale, modified for HIV populations, which assesses the endorsement of each of 12 cognitive and behavioral coping strategies. Two subscales, denial and behavioral disengagement, were combined for an avoidant coping composite because of previous work relating them to disease outcomes in HIV (4,11,14). Life event stress was assessed using the Sarason et al. (41) life events scale sum of the weighted (3 to +3) negative life events excluding health related events. Social support was assessed using the ENRICHED Social Support Instrument (ESSI) (42), a 7-item scale assessing support over the past month, with 1 item asking if participants were married/partnered or not. Cumulative average psychosocial measures were calculated by averaging the patients score from each of the first 4 assessment time points that were completed. This measure would be higher, for example, in patients who are chronically depressed rather than depressed at only baseline and provides a more reliable measure than single baseline assessment.
Statistical Methods
The main analyses used HLM (43,44) to model CD4 and VL change. HLM was chosen because it permits control for antiretroviral use at each time point, allows for prediction of slope, and the calculation of expected changes in CD4 and VL for each predictor. Variance in disease progression markers is separated into 2 levels: Level 1 represents a growth model for each individual capturing within-person change in CD4 and VL over repeated measurements. Level 2 represents a model of interindividual differences in parameters of individual change and uses between-person characteristics (e.g., depression) to predict change. Thus, systematic variability of the slopes and intercepts at level 1 are modeled by predictors at level 2.
Covariate Selection
Level 1 covariates included prescribed antiretroviral medication (as a time-dependent covariate), time since baseline (months), and the interactions of these terms. Time since baseline reflected the length of time each of the 5 repeated assessments were conducted relative to baseline and generated the structure of the latent slope and intercept. Antiretroviral medications were dummy coded at each time point, reflecting 3 levels: no medication, combination therapy, or HAART. The demographic variables of race (coded 1 = non-Hispanic Caucasian, 0 = other), gender (coded 1 = male, 0 = female), age, education level (coded 0 = less than high school, 1 = some high school, 2 = high school graduate, 3 = trade-school or some college, 4 = college graduate, 5 = graduate degree) were included as a priori covariates relevant to HIV (45,46). Education level was used as a relatively unbiased indicator of SES because income and employment may be affected by advancing HIV disease. Initial disease status was also controlled in the level 2 model using baseline CD4 number or VL log10 to account for the possibility that initial level of CD4 or VL may be related to change over time. The covariates were included, a priori, in the level 2 model at the slope (the outcome of interest) and remained in both CD4 and VL models for all subsequent analysis. All continuous variables in the model were centered, and all categorical variables were coded with zero as the lowest level. Because VL was skewed, it was transformed using a log10 transformation.
Medication Adherence
As only 77% of the sample were taking antiretroviral medication at study entry and only 90% of the sample were taking medications at any time during the study, medication adherence data were only available on a subset of the whole sample (n = 160). Because of the central role of adherence in optimal management of HIV, the main analyses were rerun to determine whether the significance of the psychosocial variables on disease progression was independent of adherence.
| RESULTS |
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Prediction to CD4 Change Over Time
Basic Model
Table 3 contains the basic equations (and explanation of terms) for the HLM model, and Table 4 includes the results and significance tests for the basic model for predicting CD4 change/slope controlling for antiretroviral medications and other covariates. There is a significant linear decrease in CD4 over time (
10) controlling for covariates. The model indicates that average CD4 level at study entry is 285.52, and this decreased at a rate of 4.45 CD4 cells/month (about 53 cells/yr) above and beyond the effects of medications for minority women of low SES (i.e., categorical variables coded 0). There is also significant individual variation in CD4 change over time (
2 (170) = 415.48, p < .001).
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Covariates
At level 1 (see Table 4), there is a significant increase in CD4 attributable to changes in being on combination therapy or HAART (
40 and
50). At level 2, higher education and higher baseline CD4 buffered CD4 decline.
The Contribution of Psychological Variables
Baseline Predictors
Faster CD4 decline was predicted from baseline depression (
16), hopelessness (
16), and social support (
16; trend) but not from avoidant coping or life event stress (Table 5a). Subsequent analysis restricting the BDI to the cognitive/affective subscale only showed a continued tendency toward significance (
16 = 0.130, t(170) = 1.602, p = .11).
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Relationship to Cumulative Variables
Cumulative depression, hopelessness, and avoidant coping were more strongly related to CD4 decline than baseline measures. The cognitive/affective subscale of the BDI was also significantly related to CD4 decline (
16 = 0.189, t(170) = 1.936, p = .05), as were both denial (
16 = 1.160, t(170) = 2.652, p = .009) and behavioral disengagement (
16 = 1.12, t(170) = 2.127, p = .035). Cumulative life events stress and social support were not significantly related to CD4 change.
Clinical Translation
Decline ratios (DRs) were calculated to compare the impact of the high and low levels (75th and 25th percentile) of each psychological variable on CD4 and VL change (see Table 5a). The formula for the calculation of the DR is: DR = [
10 +
16 (75th percentile score mean)]/[
10 +
16 (25th percentile score mean)], where
10 is the average rate of CD4 decline controlling for other covariates in the model and
16 is the increment in CD4 decline for every point above or below the mean of the psychological variable. Cumulative depression provides an illustrative example. The rate of decline for those of average depression (
10) is 3.36 CD4 cells per month (run with BDI in the model), and the increment for each point from the mean of depression (
16) is 0.21. The 75th and 25th percentile scores in cumulative depression were 14.25 and 4.25, respectively, which were 4.20 and 5.80 points from the mean, respectively. The rate of CD4 cell decline for those at the 25th percentile in depression is given by (3.36) + [(0.21) (5.80)] = 2.14 per month, or approximately 26 per year. The rate of CD4 cell decline for those at the 75th percentile in depression is given by (3.36) + [(0.21) (4.20)] = 4.24 cells per month, or approximately 51 per year. Thus those scoring at the 75th percentile in cumulative depression lose their CD4 cells at almost twice the rate compared with those at the 25th percentile, as indicated by DR = 1.96.1 Increase ratios for VL log are calculated in a parellel fashion (Table 7a).
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Other DRs for the significant psychosocial predictors are presented in Table 5a.
Prediction to VL Change Over Time
Basic Model (Table 6)
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10), controlling for covariates. Patients had an average of 4.38 VL log units at study entry and increased 0.014 U/month (0.168 log units/yr). Individual variation around the slope of VL (change) was also significant (
2 (170) = 235.62, p = .001)
Covariates (Table 6)
Antiretroviral medications were significantly associated with lower levels of VL (
20,
30). Only education was significantly related to log VL slope (t(171) = 2.207, p = .029).
The Contribution of Psychological Variables
Prediction From Baseline Variables (Table 7a)
Higher baseline depression (BDI), hopelessness (BHS), negative life events, and avoidant coping (COPE) predicted greater VL increase. The cognitive/affective subscale of the BDI showed similar results (
16 = 0.1073 x 102, t(170) = 2.325, p = .021), as did both denial (
16 = 0.433 x 102, t(170) = 2.655, p = .009) and behavioral disengagement (
16 = 0.608 x 102, t(170) = 3.298; p = .002). Baseline levels of social support were not significantly related to VL change over time.
Relationship to Cumulative Variables (Table 7a)
Cumulative depression, hopelessness, negative life events, and avoidant coping maintained their significant association with VL change. The COPE subscales of denial (
16 = 0.614 x 102, t(170) = 2.293, p = .023) and behavioral disengagement (
16 = 0.896 x 102, t(170) = 3.734, p = .001) were also significantly related to VL increase, as was the cognitive/affective subscale of the BDI (
16 = 0.150 x 102, t(170) = 2.697, p = .008). Cumulative measures of social support were not significantly related to VL change.
Clinical Translation (Table 7a)
Those with high baseline depression scores (75th percentile) experienced close to a threefold increase in VL as compared with those with low scores (25th percentile). The largest baseline increase ratio (6.41) was observed for avoidant coping. The largest cumulative increase ratio was found for depression (7.44).
Medication Adherence
Cumulative self-reported medication adherence was significantly related to each of the psychosocial predictors, except social support (see Table 8). Medication adherence was significantly associated with slope of VL (
16 = 0.042, t(153) = 2.539, p = .012) but not to CD4 change (
16 = 3.22, t(153) = 0.979, p = .330). Controlling for medication adherence in these models did not alter the significance of any of the relationships found in the main analyses (see Tables 5b and 7b), with the exception of life events stress, which had significantly predicted VL change but now showed only a trend (p = .055).
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| DISCUSSION |
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Although many studies have found that depression and other psychological variables predict disease progression in HIV, none, to our knowledge, have controlled for adherence. This has become particularly important in the era of HAART as it has been estimated that adherence rates of up to 95% are required for achieving and maintaining viral suppression (26,27). It is interesting to note that in our study, medication adherence was significantly related to VL change, but not to CD4 change. Although the reason for this is not known, it raises the possibility that VL may be more immediately responsive to antiretroviral medications than CD4 cell reconstitution, which may require a longer period of time.
Our results provide information on the predictive relationships from both baseline and repeated measures of stress, distress, and coping. The presence of a significant relationship between cumulative avoidant coping with rate of CD4 change over time compared with the absence of a significant relationship with baseline supports the use of repeated assessments over time. The superior predictive power of repeated measures over baseline measures has been noted by others (5,6,8,13) and may help to explain some of the contrary findings relating depression to disease progression when depression was only measured at baseline (47).
Surprisingly, not only did no significant results emerge between social support and disease progression but a nonsignificant trend was observed whereby higher levels of baseline social support predicted more rapid CD4 decline. This puzzling result has some support in the existent literature (20) but is not consistent with results of several other studies which identified beneficial relationships (4,7). Subsequent analyses of our data revealed that higher levels of social support were associated with being sexually active (r = 0.27, p < .001) (assessed through interview) but were not associated with unsafe sex practices (r = 0.00, not significant). Notable aspects of this study that may be related to the absence of social support findings include the restriction of study participants to those in the midrange of disease, the exclusion of IV and dependent drug users, and the use of a measure that has items but not subscales for emotional, instrumental, and informational support.
Education was the only sociodemographic covariate significantly related both to rate of CD4 and VL change. The SES-health gradient is well established in the general literature (48), but this study is the first of which we are aware to predict changes in both biological markers of disease progression in HIV.
There are a number of plausible behavioral and biological mechanisms that have been suggested in explaining the link between depression/stress and disease progression (5,49). In this sample, adherence to medication does not explain the effect. Alterations in the hypothalamic-pituitary-adrenocortical system, including cortisol, have been demonstrated both in stress and depression, have been predictive of faster disease progression in HIV (4,13), and may stimulate HIV replication (50). Similarly, products of the sympathetic nervous system (norepinephrine) become elevated during stress and have been shown to enhance HIV viral replication in vitro (51,52). Important immune variables, including cytotoxic T lymphocytes and natural killer cells, undergo change during depression in HIV patients and have been related to symptom onset and disease progression in HIV (53,54).
Limitations
Although psychosocial variables were related to important markers of disease progression (i.e., CD4, HIV VL) that are known to predict clinical outcomes (21,22), the relatively short follow-up time of this study precluded predicting to clinical symptoms or death. The longitudinal design allows for the statement of predictive but not necessarily causal relationships between our baseline psychosocial variables and disease progression markers. Another limitation of the study was that the psychosocial (e.g., negative life events) and control (e.g., medication adherence) measures are based on self-reports and are vulnerable to the biases of that methodology. For example, it has been reported that life events stress measured by interview predicts CD4 change (3), whereas the present study using self-report assessment did not (although it did predict to VL). Finally, although changes in depression were carefully measured across assessments, the treatment of depression was not tracked and was not part of these analyses.
Conclusions and Future Directions
In summary, the present study demonstrated that several psychosocial factors contribute to the variance in HIV disease progression even in the present era of HAART medication. In particular, feelings of hopelessness, depressed mood, and avoidant coping predict an accelerated decline in CD4 cells and an increase in HIV VL. Pharmacologic (55,56) and behavioral treatments (57,58) have been shown to decrease depression in HIV patients. To the extent that these treatments may also attenuate both depressed affect and disease progression, large scale clinical intervention trials are needed to determine whether reducing distress and hopelessness, and improving adaptive coping skills in HIV infected individuals can decrease disease progression. Recent findings from a study of stress management in gay men with HIV (59) suggests that this may be the case, at least for VL.
Thanks to Kelly Detz for data management and to Annie George for conducting many of the interviews.
| NOTES |
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16 = 1.73, t(170) = 2.241, p = .026) and VL change (
16 = 1.38 x 102, t(170) = 3.391, p = .001) whereby those with chronic depression experienced a loss of CD4 cells at 2.02 times the rate and an increase in VL at 5.00 times the rate as those with limited or no depression. These results are consistent with the results of the main analyses. This research was graciously supported by the National Institute of Mental Health Grant (R01MH53791 and R01MH066697) Principal Investigator: Gail Ironson, T32MH18917 and Action for AIDS Foundation.
DOI:10.1097/01.psy.0000188569.58998.c8
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