The factor structure of the PHQ-9 in palliative care

Depressive symptom dimensions and medication non-adherence in suboptimally controlled type 2 diabetes

AIMS

Research suggests differential effects for somatic and cognitive-affective depressive symptoms in predicting health outcomes. This study evaluated differential relations with medication non-adherence among disadvantaged, and predominantly immigrant adults with sub-optimally controlled type 2 diabetes (T2D).

METHODS

Health plan members taking oral diabetes medication and who had A1c ≥ 7.5% were recruited for a trial of telephonic self-management support. A subset (n = 376; age, M = 55.6 ± 7.2 years; A1c M = 9.1% ± 1.6) completed the Patient Health Questionnaire-8 (PHQ-8). Diabetes medication adherence was measured by self-report and claims-based records. Multivariable logistic regression modeled depressive symptoms and odds of non-adherence using pre-intervention data.

RESULTS

A positive PHQ-8 screen (OR = 2.72 [95%CI: 1.56-4.73]) and each standard deviation increase in PHQ-8 score (OR = 1.40 [95%CI: 1.11-1.75]) were associated with non-adherence, with no independent effects for somatic versus cognitive-affective symptoms. Exploration of individual symptoms identified three significantly associated with non-adherence in covariate-adjusted models; after adjustment for likely presence of clinical depression, only fatigue was independently associated with non-adherence (OR = 1.71 [95%CI: 1.06-2.77]).

CONCLUSIONS

Findings support depression symptom severity as a significant correlate of medication non-adherence among disadvantaged adults with T2D. Support was limited for differential associations for symptom dimensions, but findings suggest that fatigue may be associated with non-adherence independent of the likely presence of depression.

The latent structure of major depressive symptoms and its relationship with somatic disorder symptoms among Filipino female domestic workers in China

Emerging research have investigated the factor structure of major depressive disorder (MDD) symptoms based on DSM-5 nomenclature. However, to date, results have been inconsistent on what symptom-structure best represent MDD. This study examines the best fitting MDD among four competing models in a sample of overseas Filipino domestic helpers (N = 232). The results show that a two-factor model (Model 2b; Krause et al., 2010) provided the best fit. The model consist of two factors: somatic and non-somatic/affective symptoms. Somatic component includes sleep difficulties, fatigue, appetite changes, concentration difficulties, and psychomotor agitation/retardation while non-somatic/affective component covers anhedonia, depressed mood, feelings of worthlessness, and thoughts of death. Further, the results reveal a pattern where PHQ-15 somatic symptom-items have a higher significant relationship with MDD's somatic symptoms than with the MDD's non-somatic/affective symptoms. These findings suggest that the items of model 2b are appropriately embedded in their respective factors. Differentiating MDD factors have important clinical implications, particularly in the diagnosis and treatment of depression among overseas Filipino domestic helpers.

Factorial structure of the Patient Health Questionnaire-9 as a depression screening instrument for university students in Cartagena, Colombia

Previous studies on the factorial structure of the Patient Health Questionnaire (PHQ-9) have yielded divergent results, and there is no consensus on which factorial structure provides a more adequate fit. In Colombia, no precise method to estimate the factorial structure of the PHQ-9 has been used. The purpose of this study is to evaluate the factorial structure of the PHQ-9 as a depression screening tool in university students of Colombia from a model of two factors previously studied. The PHQ-9 was applied to 550 health science university students. A factorial confirmatory analysis was carried out using a structural equations model and invariance analysis. The model with one somatic factor and one non-somatic factor, achieved a better fit with invariance by gender. The PHQ-9 used as a depression screening tool used in university students in Cartagena revealed two factors, one somatic and one non-somatic with measurement invariance by gender.

Self-reported depression symptoms in haemodialysis patients: Bi-factor structures of two common measures and their association with clinical factors

OBJECTIVE

To validate the factor structure of two common self-report depression tools in a large sample of haemodialysis (HD) patients and to examine their demographic and clinical correlates, including urine output, history of depression and transplantation.

METHODS

Factor structures of the Beck Depression Inventory (BDI-II) and Patient Health Questionnaire (PHQ-9) were evaluated using confirmatory factor analysis (CFA). Data was utilised from the screening phase (n = 709) of a placebo-controlled feasibility randomised control trial (RCT) of sertraline in HD patients with mild to moderate Major Depressive Disorder. Alternative factor models including bi-factor models for the BDI-II and PHQ-9 were evaluated. Coefficient omega and omega-hierarchical were calculated.

RESULTS

For both measures, bi-factor measurement models had the overall best fit to the data, with dominant general depression factors. Omega-hierarchical for the general BDI-II and PHQ-9 factors was 0.94 and 0.88 respectively. Both general factors had high reliability (coefficient omega = 0.97 and 0.94 respectively) and explained over 85% of the explained common variance within their respective models. BDI-II and PHQ-9 general depression factors were negatively associated with age and urine output and positively with a history of depression, antidepressant use within the last 3 months and a history of failed transplantation. In adjusted regression models, age, urine output and a history of depression remained significant.

CONCLUSIONS

These data suggest that both the BDI-II and PHQ-9 are sufficiently unidimensional to warrant the use of a total score. Younger age, lower urine output and a history of depression appear consistent correlates of depression severity among HD patients.

Factorial validity and invariance of the Patient Health Questionnaire (PHQ)-9 among clinical and non-clinical populations

The Patient Health Questionnaire-9 (PHQ-9) is commonly used to screen for depressive disorder and for monitoring depressive symptoms. However, there are mixed findings regarding its factor structure (i.e., whether it has a unidimensional, two-dimensional, or bi-factor structure). Furthermore, its measurement invariance between non-clinical and clinical populations and that between patients with major depressive disorder (MDD) and MDD with comorbid anxiety disorder (AD) is unknown. Japanese adults with MDD (n = 406), MDD with AD (n = 636), and no psychiatric disorders (non-clinical population; n = 1,163) answered this questionnaire on the Internet. Confirmatory factor analyses showed that the bi-factor model had a better fit than the unidimensional and two-dimensional factor models did. The results of a multi-group confirmatory factor analysis indicated scalar invariance between the non-clinical and only MDD groups, and that between the only MDD and MDD with AD groups. In conclusion, the bi-factor model with two specific factors was supported among the non-clinical, only MDD, and MDD with AD groups. The scalar measurement invariance model was supported between the groups, which indicated the total or sub-scale scores were comparable between groups.

Palliative Care Providers' Practices Surrounding Psychological Distress Screening and Treatment: A National Survey

OBJECTIVE

To investigate how inpatient palliative care teams nationwide currently screen for and treat psychological distress.

METHODS

A web-based survey was sent to inpatient palliative care providers of all disciplines nationwide asking about their practice patterns regarding psychological assessment and treatment. Descriptive statistics were used to characterize the sample and responses, and analysis of variance was conducted to determine whether certain disciplines were more likely to utilize specific treatment modalities.

RESULTS

A total of N = 236 respondents were included in the final analyses. Providers reported that they encounter psychological distress regularly in their practice and that they screen for distress using multiple methods. When psychological distress is detected, providers reported referring patients to an average of 3 different providers (standard deviation = 1.46), most frequently a social worker (69.6%) or chaplain (65.3%) on the palliative care team. A total of 84.6% of physicians and 54.5% of nurse practitioners reported that they prescribe anxiolytics or selective serotonin reuptake inhibitors to patients experiencing psychological distress.

DISCUSSION AND CONCLUSIONS

This study revealed significant variability and redundancy in how palliative care teams currently manage psychological distress. The lack of consistency potentially stems from the variability in the composition of palliative care teams across care settings and the lack of scientific evidence for best practices in psychological care in palliative care. Future research is needed to establish best practices in the screening and treatment of psychological distress for patients receiving palliative care.

Assessment of depression before and after inpatient rehabilitation in COPD patients: Psychometric properties of the German version of the Patient Health Questionnaire (PHQ-9/PHQ-2)

BACKGROUND

Depression is a frequent comorbidity of COPD and leads to worse clinical COPD-outcomes. PHQ-9 and PHQ-2 are two widely used brief instruments to assess depression. However, psychometric properties in COPD patients are unknown. This study examines factorial validity, measurement invariance and composite reliability (CR) of PHQ-9/PHQ-2, respectively, and concordance between both tools.

METHODS

This is a secondary analysis of N = 561 COPD patients who filled out the PHQ-9 at the begin (T0), the end (T1) and 3/6/9/12 (T2/T3/T4/T5) months after pulmonary inpatient rehabilitation. Structural equation modeling was used to examine factorial validity and measurement invariance between gender, GOLD disease severity groups and over time. Concordance was assessed using Cohen's Kappa, Yules Y, positive and negative agreement.

RESULTS

A one-factor model (with one freed residual covariance) showed best model fit. At least partial scalar invariance could be established. Concordance between both instruments was substantial. 31.7% (26.2%) COPD patients showed clinically relevant depression according to PHQ-9 (PHQ-2) at T0. At T0-T2, PHQ-9 classified more patients as depressed than did PHQ-2. According to both measures, depression rates declined after rehabilitation. Reliability was high for both PHQ-9 (CR = 0.94) and PHQ-2 (CR = 0.89).

LIMITATIONS

No gold-standard (clinical interview) to assess depression was used. Therefore, diagnostic accuracy for PHQ-9/PHQ-2 remains unclear.

CONCLUSIONS

PHQ-9 and PHQ-2 fulfill important psychometric criteria (factorial validity, invariance, reliability) for measuring depression in COPD. The results support their use in clinical practice to assess severity of depression. Diagnostic accuracy to identify major/minor depression of both instruments should be examined in future studies.

Factor structure and measurement invariance across various demographic groups and over time for the PHQ-9 in primary care patients in Spain

The Patient Health Questionnaire (PHQ-9) is a widely-used screening tool for depression in primary care settings. The purpose of the present study is to identify the factor structure of the PHQ-9 and to examine the measurement invariance of this instrument across different sociodemographic groups and over time in a sample of primary care patients in Spain. Data came from 836 primary care patients enrolled in a randomized controlled trial (PsicAP study) and a subsample of 218 patients who participated in a follow-up assessment at 3 months. Confirmatory factor analysis (CFA) was used to test one- and two-factor structures identified in previous studies. Analyses of multiple-group invariance were conducted to determine the extent to which the factor structure is comparable across various demographic groups (i.e., gender, age, marital status, level of education, and employment situation) and over time. Both one-factor and two-factor re-specified models met all the pre-established fit criteria. However, because the factors identified in the two-factor model were highly correlated (r = .86), the one-factor model was preferred for its parsimony. Multi-group CFA indicated measurement invariance across different demographic groups and across time. The present findings suggest that physicians in Spain can use the PHQ-9 to obtain a global score for depression severity in different demographic groups and to reliably monitor changes over time in the primary care setting.

The DEsire to DIe in Palliative care: Optimization of Management (DEDIPOM) - a study protocol

BACKGROUND

A desire to die (DD) is frequent in palliative care (PC). However, uncertainty remains as to the appropriate therapeutic response. (Proactive) discussion of DD is not usually part of standard care. To support health practitioners' (HPs) reactions to a patient's DD, a training program has been developed, piloted and evaluated. Within this framework, a first draft of a semi-structured clinical interview schedule with prompts (CISP) has been developed, including recommendations for action to support HPs' self-confidence. The aim of this study is the further development of the CISP to support routine exploration of death and dying distress and proactive addressing of a DD.

METHODS

This observatory, prospective health services study comprises a three step study design: 1. Revision of the CISP and consensus finding based on semi-structured interviews with patients and a Delphi process with (inter-)national experts, patient representatives and relatives; 2. Increasing confidence in HPs through a 2 day-training program using the consented CISP; 3. A formative quantitative evaluation of conversations between HPs and patients (300 palliative patients at three time points) and a qualitative evaluation based on interview triads of patients, relatives and HPs. The evaluation of conversations will include patient-oriented outcomes, including perceived relationships with HPs and death and dying distress. We will also consider aspects of social inequality and gender.

DISCUSSION

The intervention can provide a framework for open discussion of DD and a basis for enhancing a trustful HP-patient relationship in which such difficult topics can be addressed. The benefits of this study will include (a) the creation of the first consented semi-structured approach to identify and address DD and to respond therapeutically, (b) the multi-professional enhancement of confidence in dealing with patients' DD and an intervention that can flexibly be integrated into other training and education programs and (c) an evaluation of effects of this intervention on patients, relatives and HPs, with attention to social inequality and gender.

TRIAL REGISTRATION

The study is registered in the German Clinical Trials Register ( DRKS00012988 ; registration date: 27.9.2017) and in the Health Services Research Database ( VfD_DEDIPOM_17_003889 ; registration date: 14.9.2017).

The prevalence of depression and the accuracy of depression screening tools in migraine patients

OBJECTIVES

Migraine and depression are common comorbid conditions. The purpose of this study was to assess how well the Patient Health Questionnaire (PHQ-9) and the Hospital Anxiety and Depression Scale (HADS) perform as depression screening tools in patients with migraine.

METHODS

Three hundred consecutive migraine patients were recruited from a large headache center. The PHQ-9 and HADS were self-administered and validated against the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV, a gold standard for the diagnosis of depression. Sensitivity, specificity, positive predictive value, negative predictive value and receiver-operator characteristic curves were calculated for the PHQ-9 and HADS.

RESULTS

At the traditional cut-point of 10, the PHQ-9 demonstrated 82.0% sensitivity and 79.9% specificity. At a cut-point of 8, the HADS demonstrated 86.5% sensitivity and specificity. The PHQ-9 algorithm performed poorly (53.8% sensitivity, 94.9% specificity). The point prevalence of depression in this study was 25.0% (95% CI 19.0-31.0), and 17.0% of patients had untreated depression.

CONCLUSIONS

In this study, the PHQ-9 and HADS performed well in migraine patients attending a headache clinic, but optimal cut-points to screen for depression vary depending on the goals of the assessment. Also, migraine patients attending a headache clinic have a high prevalence of depression and many are inadequately treated. Future studies are needed to confirm these findings and to evaluate the impact of depression screening.

Depressive Symptoms Clusters and Insulin Resistance: Race/Ethnicity as a Moderator in 2005-2010 NHANES Data

BACKGROUND

Although depression has been linked to insulin resistance, few studies have examined depressive symptom clusters.

PURPOSE

We examined whether certain depressive symptom clusters are more strongly associated with insulin resistance in a nationally representative sample, and we evaluated potential moderators and mediators.

METHODS

Respondents were 4487 adults from NHANES 2005-2010. Depressive symptoms were measured with the Patient Health Questionnaire-9 (PHQ-9), and insulin resistance was indexed by the homeostatic model assessment (HOMA) score.

RESULTS

Positive relationships between PHQ-9 total, somatic, and cognitive-affective scores and HOMA score were detected (ps <0.001). In a simultaneous model, the somatic (p = 0.017), but not the cognitive-affective (p = 0.071), score remained associated with HOMA score. We observed evidence of (a) moderation by race/ethnicity (relationships stronger in non-Hispanic Whites) and (b) mediation by body mass and inflammation.

CONCLUSIONS

The depressive symptoms-insulin resistance link may be strongest among non-Hispanic Whites and may be driven slightly more by the somatic symptoms.

Cognitive Function in Heart Failure Is Associated With Nonsomatic Symptoms of Depression But Not Somatic Symptoms

BACKGROUND

Patients with heart failure (HF) have high rates of cognitive impairment and depressive symptoms. Depressive symptoms have been associated with greater cognitive impairments in HF; however, it is not known whether particular clusters of depressive symptoms are more detrimental to cognition than others.

OBJECTIVE

The aim of this study was to identify whether somatic and/or nonsomatic depressive symptom clusters were associated with cognitive function in persons with HF.

METHODS

Participants were 326 HF patients (40.5% women, 26.7% non-white race-ethnicity, aged 68.6 ± 9.7 years). Depressive symptoms were measured using a depression questionnaire commonly used in medical populations: the Patient Health Questionnaire-9. Somatic and nonsomatic subscale scores were created using previous factor analytic results. A neuropsychological battery tested attention, executive function, and memory. Composites were created using averages of age-adjusted scaled scores. Regressions adjusting for demographic and clinical factors were conducted.

RESULTS

Regressions revealed that Patient Health Questionnaire-9 total was associated with attention (β = -.14, P = .008) and executive function (β = -.17, P = .001). When analyzed separately, the nonsomatic subscale, but not the somatic symptoms subscale (P values ≥ .092), was associated with attention scores (β = -.15, P = .004) and memory (β = -.11, P = .044). Both nonsomatic (β = -.18, P < .001) and somatic (β = -.11, P = .048) symptoms were related to executive function. When included together, only the nonsomatic symptom cluster was associated with attention (β = -.15, P = .020) and executive function (β = -.19, P = .003).

CONCLUSIONS

Greater overall depressive symptom severity was associated with poorer performance on multiple cognitive domains, an effect driven primarily by the nonsomatic symptoms of depression.

CLINICAL IMPLICATIONS

These findings suggest that screening explicitly for nonsomatic depressive symptoms may be warranted and that the mechanisms underlying the depression-cognitive function relationship in HF are not solely related to sleep or appetite disturbance. Thus, interventions that target patients' somatic symptoms only (eg, poor appetite or fatigue) may not yield maximum cognitive benefit compared with a comprehensive treatment that targets depressed mood, anhedonia, and other nonsomatic symptoms.

Assessment of depression severity with the PHQ-9 in cancer patients and in the general population

BACKGROUND

The Patient Health Questionnaire PHQ-9 is a widely used instrument to screen for depression in clinical research. The first aim of this study was to psychometrically test the PHQ-9 in a large sample of cancer patients. The second aim was to calculate unbiased estimates of the depression burden for several cancer groups taking into account age and gender distributions.

METHODS

A sample of 2,059 cancer patients with varying diagnoses were examined in this study six months after discharge from a rehabilitation clinic. A representative sample of 2,693 people from the general population served as controls. Expected PHQ-9 mean scores of the general population sample, regressed on age and gender, were calculated to enable a fair comparison of different groups of cancer patients.

RESULTS

While the reliability (Cronbach's alpha) for the PHQ-9 scale was good (alpha ≥ 0.84), the CFA fit indices of the one-dimensional solution were unsatisfactory in the patients' sample. The factorial analysis confirmed two factors. PHQ-9 mean scores for 15 types of cancer are given, ranging from 4.0 (prostate) to 8.2 (thyroid gland). Differences between expected mean scores (derived from the general population) and raw mean scores of the cancer subsamples are reported that provide a better estimate of the depression burden.

CONCLUSIONS

The results confirmed that the PHQ-9 performs well in testing depression in cancer patients. Regression coefficients can be used for performing unbiased comparisons among cancer groups, not only for this study. The burden of patients with testis cancer and Hodgkin lymphoma is underestimated when age and gender are not taken into account.

Validity and diagnostic accuracy of the Luganda version of the 9-item and 2-item Patient Health Questionnaire for detecting major depressive disorder in rural Uganda

BACKGROUND

The prevalence of depression in rural Ugandan communities is high and yet detection and treatment of depression in the primary care setting is suboptimal. Short valid depression screening measures may improve detection of depression. We describe the validation of the Luganda translated nine- and two-item Patient Health Questionnaires (PHQ-9 and PHQ-2) as screening tools for depression in two rural primary care facilities in Eastern Uganda.

METHODS

A total of 1407 adult respondents were screened consecutively using the nine-item Luganda PHQ. Of these 212 were randomly selected to respond to the Mini International Neuropsychiatric Interview diagnostic questionnaire. Descriptive statistics for respondents' demographic characteristics and PHQ scores were generated. The sensitivity, specificity and positive predictive values (PPVs), and area under the ROC curve were determined for both the PHQ-9 and PHQ-2.

RESULTS

The optimum trade-off between sensitivity and PPV was at a cut-off of ≧5. The weighted area under the receiver Operating Characteristic curve was 0.74 (95% CI 0.60-0.89) and 0.68 (95% CI 0.54-0.82) for PHQ-9 and PHQ-2, respectively.

CONCLUSION

The Luganda translation of the PHQ-9 was found to be modestly useful in detecting depression. The PHQ-9 performed only slightly better than the PHQ-2 in this rural Ugandan Primary care setting. Future research could improve on diagnostic accuracy by considering the idioms of distress among Luganda speakers, and revising the PHQ-9 accordingly. The usefulness of the PHQ-2 in this rural population should be viewed with caution.

Validity of single item responses to short message service texts to monitor depression: an mHealth sub-study of the UK ACUDep trial

Background

An increasing number of research designs are using text messaging (SMS) as a means of self-reported symptom and outcome monitoring in a variety of long-term health conditions, including severity ratings of depressed mood. The validity of such a single item SMS score to measure latent depression is not currently known and is vital if SMS data are to inform clinical evaluation in the future.

Methods

A sub-set of depressed participants in the UK ACUDep trial submitted a single SMS text score (R-SMS-DS) between 1 and 9 on how depressed they felt around the same time as completing the PHQ-9 depression questionnaire on paper at 3 months follow-up of the trial. Exploratory categorical data factor analysis (EFA) was used to ascertain the alignment of R-SMS-DS scores with the factor structure of the PHQ-9. Any response bias with regard to age or gender was assessed by differential item functioning (DIF) analysis.

Results

Depression scores based on the PHQ-9 and R-SMS-DS at 3 months were available for 337 participants (74 % female; mean age: 42 years, SD = 11.1), 213 of which completed the two outcomes within 6 days of each other. R-SMS-DS scores aligned with the underlying latent depression of the PHQ-9 (factor loading of 0.656) and in particular its affective rather than somatic dimension. The R-SMS-DS score was most strongly correlated with depressed mood (r = 0.607), feeling bad about oneself (r = 0.588) and anhedonia (r = 0.573). R-SMS-DS responses were invariant with respect to gender (p = 0.302). However, there was some evidence for age related response bias (p = 0.031), with older participants being more likely to endorse lower R-SMS-DS scores than younger ones.

Conclusions

The R-SMS-DS used in the ACUDep trial was found to be a valid measure of latent affective depression with no gender related response bias. This text message item may therefore represent a useful assessment and monitoring tool meriting evaluation in further research. For future study designs we recommend the collection of outcome data by new health technologies in combination with gold standard instruments to ensure concurrent validity.

Validation of patient health questionnaire (PHQ) for major depression in Chinese outpatients with multiple somatic symptoms: a multicenter cross-sectional study

BACKGROUND

Despite the high co-morbidity of depressive symptoms in patients with multiple somatic symptoms, the validity of the 9-item Patient Health Questionnaire (PHQ-9) has not yet been investigated in Chinese patients with multiple somatic symptoms.

METHODS

The multicenter cross-sectional study was conducted in ten outpatient departments located in four cities in China. The psychometric properties of the PHQ-9 were examined by confirmative factor analysis (CFA). Criterion validation was undertaken by comparing results with depression diagnoses obtained from the Mini International Neuropsychiatric Interview (MINI) as the gold standard.

RESULTS

Overall, 491 patients were recruited of whom 237 had multiple somatic symptoms (SOM+ group, PHQ-15≥10). Cronbach׳s α of the PHQ-9 was 0.87, 0.87, and 0.90 for SOM+ patients, SOM- patients, and total sample respectively. All items and the total score were moderately correlated. The factor models of PHQ-9 tested by CFA yielded similar diagnostic performance when compared to sum score estimation. Multi-group confirmatory factor analysis based on unidimensional model showed similar psychometric properties over the groups with low and high somatic symptom burden. The optimal cut-off point to detect depression in Chinese outpatients was 10 for PHQ-9 (sensitivity=0.77, specificity=0.76) and 3 for PHQ-2 (sensitivity=0.77, specificity=0.74).

LIMITATIONS

Potential selection bias and nonresponse bias with applied sampling method.

CONCLUSIONS

PHQ-9 (cut-off point=10) and PHQ-2 (cut-off point=3) were reliable and valid to detect major depression in Chinese patients with multiple somatic symptoms.

Race/ethnicity moderates the relationship between depressive symptom severity and C-reactive protein: 2005-2010 NHANES data

Because few studies have examined depression facets or potential moderators of the depression-inflammation relationship, our aims were to determine whether particular depressive symptom clusters are more strongly associated with C-reactive protein (CRP) levels and whether race/ethnicity moderates these relationships. We examined data from 10,149 adults representative of the U.S. population (4858 non-Hispanic White, 1978 non-Hispanic Black, 2260 Mexican American, 1053 Other Hispanic) who participated in the cross-sectional National Health and Nutrition Examination Survey between 2005 and 2010. Depressive symptoms were assessed by the Patient Health Questionnaire-9, and high-sensitivity serum CRP was quantified by latex-enhanced nephelometry. Total (p<.001), somatic (p<.001), and nonsomatic (p=.001) depressive symptoms were each positively related to serum CRP in individual models. However, in the simultaneous model that included both symptom clusters, somatic symptoms (p<.001), but not nonsomatic symptoms (p=.98), remained associated with serum CRP. Evidence of moderation by race/ethnicity was also observed, as six of the nine depressive symptoms×race/ethnicity interactions were significant (ps<.05). Among non-Hispanic Whites, the pattern of results was identical to the full sample; only somatic symptoms (p<.001) remained related to serum CRP in the simultaneous model. No relationships between total, somatic, or nonsomatic symptoms and serum CRP were observed among the non-Hispanic Black, Mexican American, or Other Hispanic groups. Our findings indicate that the link between depressive symptoms and systemic inflammation may be due to the somatic symptoms of sleep disturbance, fatigue, appetite changes, and psychomotor retardation/agitation and may be strongest among non-Hispanic Whites.

Negative affectivity as a transdiagnostic factor in patients with common mental disorders

BACKGROUND

Screening and monitoring systems are increasingly used in psychotherapy, but it has been questioned whether outcome measurement using multiple questionnaires is warranted. Arguably, type and number of assessment instruments should be determined by empirical research. This study investigated the latent factor structure of a multi-dimensional outcome measurement strategy used in English services aligned to the Improving Access to Psychological Therapies (IAPT) programme.

METHODS

Factor analyses and structural equation models were performed on 11,939 intake assessments of outpatients accessing an IAPT service between 2008 and 2010. We examined whether three routinely employed instruments (PHQ-9 for depression, GAD-7 for anxiety, WSAS for functional impairment) assess empirically different dimensions.

RESULTS

The instruments were found to assess mainly one general dimension and only some items of the GAD-7 and WSAS assess unique variance beyond this general dimension. In a structural equation model the disorder-specific factor scores were predicted by patients׳ diagnostic categories.

LIMITATIONS

Since a large naturalistic data base was used, missing data for diagnoses and scale items were encountered. Diagnoses were obtained with brief case-finding measures rather than structured diagnostic interviews.

CONCLUSION

Although the items seem to address mostly one dimension, some variance is due to differences between individuals in anxiety and impairment. While this generally supports multi-dimensional assessment in a primary care population, the clinical upshot of the study is to concentrate attention on transdiagnostic factors as a target for treatment.