Measurement Invariance of Scores on the Somatic Symptom Scale-8: National Sample of Non-Clinical Adults in the United States.

Objective: The aim of the present study was to test the factorial invariance and convergent validity evidence of scores on the Somatic Symptom Scale (SSS)-8 with a national sample of adults living in the United States. Method: A data collection contracting service was hired to recruit a national, non-clinical sample (N = 821) of adults in the United States stratified by the census data for age, gender, ethnicity, and geographic location. Results: Factorial invariance testing via multiple-group confirmatory factor analysis revealed strong factorial invariance evidence (configural, metric, and scalar) of SSS-8 scores across gender, ethnicity, help-seeking history, education, and income. Convergent validity testing displayed strong correlations between SSS-8 scores and the following established measures: Patient Health Questinaire-9, Generalized Anxiety Disorder-7, and Mental Health Inventory-5. Conclusion: Collectively, the results suggest that professional counselors can use the SSS-8 to enhance somatic symptomology screening efforts with adults living in the United States.

Detecting DSM-5 somatic symptom disorder: criterion validity of the Patient Health Questionnaire-15 (PHQ-15) and the Somatic Symptom Scale-8 (SSS-8) in combination with the Somatic Symptom Disorder - B Criteria Scale (SSD-12).

BACKGROUND: The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) introduced somatic symptom and related disorders (SSD) to improve the diagnosis of somatoform disorders. It is unclear whether existing questionnaires are useful to identify patients with SSD. Our study investigates the diagnostic accuracy of the Patient Health Questionnaire-15 (PHQ-15) and the Somatic Symptom Scale-8 (SSS-8) in combination with the Somatic Symptom Disorder - B Criteria Scale (SSD-12). METHODS: For this cross-sectional study, participants were recruited from a psychosomatic outpatient clinic. PHQ-15, SSS-8, and SSD-12 were administered and compared with SSD criteria from a diagnostic interview. Sensitivity and specificity were calculated for optimal individual and combined cutpoints. Receiver operator curves were created and area under the curve (AUC) analyses assessed. RESULTS: Data of n = 372 patients [31.2% male, mean age: 39.3 years (s.d. = 13.6)] were analyzed. A total of 56.2% fulfilled the SSD criteria. Diagnostic accuracy was moderate for each questionnaire (PHQ-15: AUC = 0.70; 95% CI = 0.65-0.76; SSS-8: AUC = 0.71; 95% CI = 0.66-0.77; SSD-12: AUC = 0.74; 95% CI = 0.69-0.80). Combining questionnaires improved diagnostic accuracy (PHQ-15 + SSD-12: AUC = 0.77; 95% CI = 0.72-0.82; SSS-8 + SSD-12: AUC = 0.79; 95% CI = 0.74-0.84). Optimal combined cutpoints were ⩾9 for the PHQ-15 or SSS-8, and ⩾23 for the SSD-12 (sensitivity and specificity = 69% and 70%). CONCLUSIONS: The combination of the PHQ-15 or SSS-8 with the SSD-12 provides an easy-to-use and time- and cost-efficient opportunity to identify persons at risk for SSD. If systematically applied in routine care, effective screening and subsequent treatment might help to improve quality of life and reduce health care excess costs.

How symptoms of simple acute infections affect the SSS-8 and SSD-12 as screening instruments for somatic symptom disorder in the primary care setting.

Objective: Somatic symptom disorder (SSD) is one of the most common reasons for consultations in primary care, in addition to simple acute infections. Questionnaire-based screening instruments to identify patients at high risk of SSD are thus of great clinical relevance. Although screening instruments are frequently used, it is currently unclear to what extent they are influenced by the concurrent presence of simple acute infections. Therefore, this study aimed to investigate how symptoms of simple acute infections affect the two established questionnaires as screening instruments for somatic symptom disorder in the primary care setting. Methods: In our cross-sectional, multicenter design, a total of 1,000 patients in primary care practices were screened using the two most established SSD screening questionnaires, the 8-item Somatic Symptom Scale (SSS-8) and the 12-item Somatic Symptom Disorder-B Criteria Scale (SSD-12), followed by clinical assessment by the primary care physician. Results: A total of 140 patients with a simple acute infection (acute infection group, AIG) and 219 patients with chronic somatic symptoms (somatic symptom group, SSG) were included. The patients in the SSG showed higher total SSS-8 and SSD-12 scores than the patients in the AIG; however, the SSS-8 was more susceptible to changes triggered by symptoms of a simple acute infection than the SSD-12. Conclusion: These results suggest that the SSD-12 is less susceptible to symptoms of a simple acute infection. Its total score and corresponding cutoff value provide a more specific and thus less susceptible screening tool for identifying SSD in primary care.

Detecting DSM-5 somatic symptom disorder in general hospitals in China: B-criteria instrument has better accuracy-A secondary analysis.

Objective: This study investigates the diagnostic accuracy of the PHQ-15, SSS-8, SSD-12 and Whitley 8 and their combination in detecting DSM-5 somatic symptom disorder in general hospitals. Methods: In our former multicenter cross-sectional study enrolling 699 outpatients from different departments in five cities in China, SCID-5 for SSD was administered to diagnose SSD and instruments including PHQ-15, SSS-8, SSD-12 and WI-8 were used to evaluate the SSD A and B criteria. In this secondary analysis study, we investigate which instrument or combination of instrument has best accuracy for detecting SSD in outpatients. Receiver operator curves were created, and area under the curve (AUC) analyses were assessed. The sensitivity and specificity were calculated for the optimal individual cut points. Results: Data from n = 694 patients [38.6% male, mean age: 42.89 years (SD = 14.24)] were analyzed. A total of 33.9% of patients fulfilled the SSD criteria. Diagnostic accuracy was moderate or good for each questionnaire (PHQ-15: AUC = 0.72; 95% CI = 0.68-0.75; SSS-8: AUC = 0.73; 95% CI = 0.69-0.76; SSD-12: AUC = 0.84; 95% CI = 0.81-0.86; WI-8: AUC = 0.81; 95% CI = 0.78-0.84). SSD-12 and WI-8 were significantly better at predicting SSD diagnoses. Combining PHQ-15 or SSS-8 with SSD-12 or WI-8 showed similar diagnostic accuracy to SSD-12 or WI-8 alone (PHQ-15 + SSD-12: AUC = 0.84; 95% CI = 0.81-0.87; PHQ-15 + WI-8: AUC = 0.82; 95% CI = 0.79-0.85; SSS-8 + SSD-12: AUC = 0.84; 95% CI = 0.81-0.87; SSS-8 + WI-8: AUC = 0.82; 95% CI = 0.79-0.84). In the efficiency analysis, both SSD-12 and WI-8 showed good efficiency, SSD-12 slightly more efficient than WI-8; however, within the range of good sensitivity, the PHQ-15 and SSS-8 delivered rather poor specificity. For a priority of sensitivity over specificity, the cutoff points of ≥13 for SSD-12 (sensitivity and specificity = 80 and 72%) and ≥17 for WI-8 (sensitivity and specificity = 80 and 67%) are recommended. Conclusions: In general hospital settings, SSD-12 or WI-8 alone may be sufficient for detecting somatic symptom disorder, as effective as when combined with the PHQ-15 or SSS-8 for evaluating physical burden.

Translation and validation of the Greek version of the Somatic Symptom Scale-8 (SSS-8) in patients with chronic low back pain.

PURPOSE: To translate and validate the Greek version of the Somatic Symptom Scale-8 (SSS-8) in patients with chronic low back pain (CLBP). MATERIALS AND METHODS: The Greek SSS-8, created through forth and back translation and cultural adaption processes, was handed over to 145 patients recruited using simple random sampling. Test-retest, composite, and internal consistency reliability were assessed. Construct validity was examined by assessing correlations with Patient Health Questionnaire-15 (PHQ-15), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and EuroQoL 5-dimension 5-level (EQ-5D-5L) instruments. Structural validity was assessed using confirmatory factor analysis (CFA). Convergent, discriminant, and known group validity were also evaluated. RESULTS: The response rate was 95.1% (138 subjects, mean age 43.2 ± 11.7) and the overall Cronbach's alpha was 0.831. Test-retest reliability assessment revealed excellent results (Pearson's r > 0.996; Lin's concordance coefficient > 0.995; intraclass correlation coefficient >0.995, all p < 0.001). Composite reliability scores for the pain, cardiopulmonary, and fatigue domains were 0.712, 0.787, and 0.567, respectively. The correlation analyses indicated good construct validity. CFA revealed excellent fit results and known group validity output indicated a linear increasing trend in the severity of somatic symptom disorders (SSDs), depression, and anxiety with higher PHQ-15, PHQ-9, and GAD-7 scores (Jonckheere-Terpstra test, p value < 0.001). CONCLUSIONS: The Greek SSS-8 was shown to be a reliable and valid tool for measuring SSDs in patients with CLBP.Implications for RehabilitationAccording to the Global Burden of Diseases Study 2017, LBP was one of the leading causes of disability for both sexes combined since 1990.Strategies to identify SSDs in patients with LBP at an earlier stage are essential both for the provision of an optimal targeted treatment and for minimizing its direct and indirect economic burden.The Greek SSS-8 is a standardized and validated instrument, which its utilization will enhance the physical therapy assessment process in the Greek population.Not only is the SSS-8 an easy-to-use and highly accurate diagnostic tool for detecting SSDs, but also a short alternative to PHQ-15 in settings with limited assessment time.

Comparing the Patient Health Questionnaire - 15 and the Somatic Symptom Scale - 8 as measures of somatic symptom burden.

PURPOSE: The Patient Health Questionnaire - 15 (PHQ-15) and the Somatic Symptom Scale - 8 (SSS-8) are self-report measures which assess somatic symptom burden. The present study investigates whether the two measures are comparable in terms of their psychometric properties and estimates of symptom burden. METHOD: Item characteristics, reliability, symptom severity and construct validity with regard to other relevant psychological, health-related quality of life and disability measures were compared for the PHQ-15m and the SSS-8 in 294 primary care patients who participated in a randomized comparative effectiveness trial targeting pain and mood symptoms. RESULTS: The reliabilities of the PHQ-15m and the SSS-8 were α=0.66 and α=0.72, respectively. Both measures were highly correlated (r=0.79). All item characteristics were comparable and both instruments showed the same pattern of correlations with instruments measuring depression, anxiety, pain, quality of life and impairment (r=0.25 to 0.53). A 1-point score increase (worsening of somatic symptoms) on either instrument resulted in a 3.7% to 3.9% increase in the number of disability days reported for the last four weeks. Using the same severity thresholds (5: low, 10: medium, 15: high), both measures identified nearly identical subgroups of patients with regard to health-related quality of life and disability. CONCLUSION: The PHQ-15m and the SSS-8 are comparable measures in terms of reliability and validity and severity classifications. These findings are in line with previous results and support the use of the SSS-8 as a valuable and short alternative to the original PHQ-15 in settings with limited assessment time.

Monitoring somatic symptoms in patients with mental disorders: Sensitivity to change and minimal clinically important difference of the Somatic Symptom Scale - 8 (SSS-8).

OBJECTIVE: The SSS-8 is a brief questionnaire for the assessment of somatic symptom burden. This study examines its sensitivity to change and the minimal clinically important difference (MCID) in patients with mental disorders. METHOD: 55 outpatients with mental disorders completed the SSS-8 and measures of anxiety, depression, and disability before and after receiving treatment. Effect sizes and correlations between the change scores were calculated. The MCID was estimated using a one standard error of measurement threshold and the change in disability as an external criterion. RESULTS: There was a medium decline in somatic symptom burden for the complete sample (n=55, dz=0.53) and a large decline in a subgroup with very high somatic symptom burden at baseline (n=11, dz=0.94). Decreases in somatic symptom burden were associated with decreases in anxiety (r=0.68, p<0.001), depression (r=0.62, p<0.001) and disability (r=0.51, p<0.001). The MCID was estimated as a 3-point decrease. CONCLUSION: The SSS-8 is sensitive to change. A 3-point decrease reflects a clinically important improvement. Due to its brevity and sound psychometric properties, the SSS-8 is useful for monitoring somatic symptom burden.

Assessing somatic symptom burden: a psychometric comparison of the patient health questionnaire-15 (PHQ-15) and the somatic symptom scale-8 (SSS-8).

OBJECTIVE: The Patient Health Questionnaire-15 (PHQ-15) is a frequently used questionnaire to assess somatic symptom burden. Recently, the Somatic Symptom Scale-8 (SSS-8) has been published as a short version of the PHQ-15. This study examines whether the instruments' psychometric properties and estimates of symptom burden are comparable. METHODS: Psychosomatic outpatients (N=131) completed the PHQ-15, the SSS-8 and other questionnaires (PHQ-9, GAD-7, WI-7, SF-12). Item characteristics and measures of reliability, validity, and symptom severity were determined and compared. RESULTS: The reliabilities of the PHQ-15 and SSS-8 were α=0.80 and α=0.76, respectively and both scales were highly correlated (r=0.83). The item characteristics were comparable. Both instruments showed the same pattern of correlations with measures of depression, anxiety, health anxiety and health-related quality of life (r=0.32 to 0.61). On both scales a 1-point increase was associated with a 3% increase in health care use. The percentile distributions of the PHQ-15 and the SSS-8 were similar. Using the same thresholds for somatic symptom severity (5, 10, and 15 points), both instruments identified nearly identical subgroups of patients with respect to health related quality of life. CONCLUSION: The PHQ-15 and the SSS-8 showed similar reliability and validity but the comparability of severity classifications needs further evaluation in other populations. Until then we recommend the use of the previously established thresholds. Overall, the SSS-8 performed well as a short version of the PHQ-15 which makes it preferable for assessment in time restricted settings.