The Somatic Symptom Scale–8
Original Investigation Research
measure. J Gen Intern Med. 2001;16(9):606-613. doi:10.1046/j.1525-1497.2001.016009606.x. 31. Löwe B, Unützer J, Callahan CM, Perkins AJ, Kroenke K. Monitoring depression treatment outcomes with the Patient Health Questionnaire–9. Med Care. 2004;42(12):1194-1201. 32. Löwe B, Kroenke K, Herzog W, Gräfe K. Measuring depression outcome with a brief self-report instrument: sensitivity to change of the Patient Health Questionnaire (PHQ-9). J Affect Disord. 2004;81(1):61-66. doi:10.1016/S0165-0327 (03)00198-8. 33. Shih T-H, Fan X. Comparing response rates from web and mail surveys: a meta-analysis. Field Methods. 2008;20(3):249-271. doi:10.1177/ 1525822X08317085.
34. Horn PSV, Green KE, Martinussen M. Survey response rates and survey administration in counseling and clinical psychology: a meta-analysis. Educ Psychol Meas. 2009;69(3):389-403. doi:10.1177/0013164408324462.
38. Kroenke K. Efficacy of treatment for somatoform disorders: a review of randomized controlled trials. Psychosom Med. 2007;69(9):881-888. doi:10.1097/ PSY.0b013e31815b00c4.
35. Copay AG, Subach BR, Glassman SD, Polly DW Jr, Schuler TC. Understanding the minimum clinically important difference: a review of concepts and methods. Spine J. 2007;7(5):541-546. doi:10.1016/j.spinee.2007.01.008.
39. Henningsen P, Zipfel S, Herzog W. Management of functional somatic syndromes. Lancet. 2007;369(9565):946-955. doi:10.1016/S01406736(07)60159-7.
36. Löwe B, Spitzer RL, Gräfe K, et al. Comparative validity of three screening questionnaires for DSM-IV depressive disorders and physicians’ diagnoses. J Affect Disord. 2004;78(2):131-140.
40. Klinkman MS. Competing demands in psychosocial care: a model for the identification and treatment of depressive disorders in primary care. Gen Hosp Psychiatry. 1997;19(2):98-111. doi:10.1016/S0163-8343(96)00145-4.
37. Jackson JL, O’Malley PG, Kroenke K. Antidepressants and cognitive-behavioral therapy for symptom syndromes. CNS Spectr. 2006;11(3):212-222.
Invited Commentary
Assessing Somatic Symptoms in Clinical Practice Arthur J. Barsky, MD
The interesting study by Gierk et al1 tests the psychometric properties of a brief, self-report somatic symptom inventory and raises several broader questions about the sources of somatic symptoms and the use of symptom inventories in clinical practice. As the authors point out, routine clinical asRelated article page 399 sessment of somatic symptoms has many functions: although obviously serving as guideposts to aid in diagnosis, they are also important in their own right as indexes of suffering and distress and can be used to assess the effectiveness of treatment over time. Somatic symptoms are a complex and multidetermined phenomenon, and they do not bear a fixed, one-to-one relationship with medical morbidity. Their close association with psychiatric disorders, particularly anxiety and depressive disorder, is well established and has been confirmed again in this study. Thus, Gierk and colleagues found that somatic symptoms were more highly correlated with anxiety and depression than with self-reported general health. Therefore, it should not be surprising that there is a substantial body of psychiatric literature on the prevalence, incidence, and nature of somatic symptoms as concomitants of psychiatric disorder. The Somatic Symptom Scale–8 (SSS-8) used in this study is derived from the Patient Health Questionnaire–15, a somatization scale that was developed to assess the somatic symptoms that frequently accompany psychiatric disorders rather than serious medical diseases, that is, to assess somatization rather than medical morbidity. The component items of the SSS-8, therefore, are closely associated with psychiatric distress, medically unexplained symptoms, and diagnosable somatoform disorders. This close association of somatic symptoms w ith psychiatric disorders is one reason that approximately one-third of the symptoms reported by patients in primary care and specialty medical settings remain jamainternalmedicine.com
medically unexplained after adequate evaluation.2 This of course does not invalidate their use in the general medical setting but does underscore the fact that they are tapping psychiatric disorder as much as medical disorder. The lack of a one-to-one relationship between somatic symptoms and medical morbidity is also apparent in the enormous interindividual variability seen in the symptoms of patients with the same severity and extent of medical disease. This has been documented in conditions as diverse as degenerative disk disease, coronary artery disease, asthma, anemia, diabetes mellitus, cholelithiasis, insomnia, and benign prostatic hypertrophy. Even when significant medical disease is present, patients’ symptoms may nonetheless be unrelated to their disease, the association being coincidental rather than causal. Symptoms that appear to be disease specific may not in fact be caused by the ostensible disease.3 When putative disease-specific symptoms (eg, headache and fatigue) have high base rates in the general population and the disease is common (eg, hypertension), the symptoms and disease are likely to occur concomitantly on a statistical basis alone.4 Somatic symptoms can even result from learning for the first time that one has a medical condition that was previously asymptomatic. Thus, receiving the initial diagnosis of hypertension is associated with the onset of symptoms commonly assumed to be caused by hypertension (eg, headache, dizziness, weakness, and epistaxis), even after controlling for the initiation of antihypertensive therapy.5 To add to the complexity of the phenomenology of somatic symptoms, epidemiologic surveys of ostensibly healthy nonpatient populations reveal that bothersome symptoms are prevalent among people with no serious medical and psychiatric disorders.6 As many as 80% to 90% of adults experience at least 1 symptom every 1 to 3 weeks,7and only 19% to 27% of people report having had no symptoms in the previous 3 days.8 Thus, 14% to 45% of American adults report being bothered JAMA Internal Medicine March 2014 Volume 174, Number 3
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archinte.jamanetwork.com/ by a University of Birmingham User on 05/31/2015
407
Research Original Investigation
The Somatic Symptom Scale–8
by headache, 19% to 39% report fatigue, 32% to 50% report back pain, and 5% to 23% report dizziness. All of this information provides a broader context for considering the study by Gierk et al. First, the survey was conducted in a community-dwelling sample—not a medical one— and the relationship between their symptoms and those of patients encountered in medical practice requires further investigation, as the authors emphasize. These differences might be quite substantial, which is suggested by the very low scores reported by the respondents (mean, 3.23, on a scale with a maximum score of 32). In addition, the medical significance of the symptoms that were reported is unclear. They may well represent the transient dysfunctions and benign, self-limited ailments that are an endemic reservoir of distress inherent in daily life rather than reflect serious medical or psychiatric morbidity. In this sense, the symptoms reported by the communitydwelling survey participants likely differ substantially from the symptoms reported by medical patients. The study also raises interesting questions about the natural history of the symptoms reported. The investigators chose to ask about current (in the past week) symptoms. It will be important in future work to determine how transient such symptoms are. There is a clinical aphorism that 90% of symptoms that on initial presentation have no clear medical basis will be transient and self-limited, subsiding within 2 weeks. The validity of this adage needs to be tested. The authors have gone a considerable distance in demonstrating the internal reliability and convergent and concurrent validity of their scale, for example, finding it significantly associated with self-reported use of medical care. Future work will need to examine this association more closely using objective measures of medical care use, since patient recall over periods as long as 1 year is generally inaccurate and unreliARTICLE INFORMATION Author Affiliations: Department of Psychiatry, Brigham and Women’s Hospital, Boston, Massachusetts; Department of Psychiatry, Harvard Medical School, Boston, Massachusetts. Corresponding Author: Arthur J. Barsky, MD, Department of Psychiatry, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115 (abarsky @partners.org). Published Online: November 25, 2013. doi:10.1001/jamainternmed.2013.12177. Conflict of Interest Disclosures: None reported. REFERENCES 1. Gierk B, Kohlmann S, Kroenke K, et al. The Somatic Symptom Scale–8 (SSS-8): a brief measure
408
able. The relationship between symptoms and medical helpseeking is of particular interest at the ends of the spectrum: stoical and underserved populations who endure substantial distress and significant disease without seeking medical attention at one extreme and, at the opposite end of the spectrum, those who visit physicians repeatedly in the absence of significant medical or psychiatric morbidity. As concerns about the costs of care rise, we need to know much more about the ways in which people act or do not act on their symptoms. It will likewise be important in future work to examine the association between these somatic symptoms and objective measures of medical morbidity. Self-reported physical health is not necessarily closely correlated with objective measures of health status as assessed with a medical record audit or a physician rating. Obviously, such case-by-case assessment of medical morbidity is not possible in a large population-based survey such as this one. In addition, computerized methods of indexing aggregate medical morbidity from the medical records or pharmacy records are difficult to develop. Although the relationship between somatic symptoms and medical morbidity is complex and fickle, none of this undermines the importance of symptoms in and of themselves, regardless of their source. They are a source of suffering and distress and thus a critical objective of all medical care. The absence of a serious medical cause for some symptoms in no way invalidates or delegitimizes them. Integration of the SSS-8 into routine, measurementbased care would constitute a substantial advance. An instrument with excellent psychometric properties like those of the SSS-8 is necessary for research to further our understanding of the phenomenology, epidemiology, natural history, and treatment response of somatic symptoms.
of somatic symptom burden [published online November 25, 2013]. JAMA Intern Med. doi:10.1001/jamainternmed.2013.12179.
5. Alderman MH, Lamport B. Labelling of hypertensives: a review of the data. J Clin Epidemiol. 1990;43(2):195-200.
2. Kroenke K. Patients presenting with somatic complaints: epidemiology, psychiatric comorbidity and management. Int J Methods Psychiatr Res. 2003;12(1):34-43.
6. Kroenke K, Price RK. Symptoms in the community: prevalence, classification, and psychiatric comorbidity. Arch Intern Med. 1993;153(21):2474-2480.
3. Kroenke K. Studying symptoms: sampling and measurement issues. Ann Intern Med. 2001;134(9, pt 2):844-853.
7. White KL, Williams TF, Greenberg BG. The ecology of medical care. N Engl J Med. 1961;265:885-892.
4. Novy D, Berry MP, Palmer JL, Mensing C, Willey J, Bruera E. Somatic symptoms in patients with chronic non–cancer-related and cancer-related pain. J Pain Symptom Manage. 2005;29(6): 603-612.
8. Khosla PP, Bajaj VK, Sharma G, Mishra KC. Background noise in healthy volunteers—a consideration in adverse drug reaction studies. Indian J Physiol Pharmacol. 1992;36(4):259-262.
JAMA Internal Medicine March 2014 Volume 174, Number 3
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archinte.jamanetwork.com/ by a University of Birmingham User on 05/31/2015
jamainternalmedicine.com
Original Investigation Research
measure. J Gen Intern Med. 2001;16(9):606-613. doi:10.1046/j.1525-1497.2001.016009606.x. 31. Löwe B, Unützer J, Callahan CM, Perkins AJ, Kroenke K. Monitoring depression treatment outcomes with the Patient Health Questionnaire–9. Med Care. 2004;42(12):1194-1201. 32. Löwe B, Kroenke K, Herzog W, Gräfe K. Measuring depression outcome with a brief self-report instrument: sensitivity to change of the Patient Health Questionnaire (PHQ-9). J Affect Disord. 2004;81(1):61-66. doi:10.1016/S0165-0327 (03)00198-8. 33. Shih T-H, Fan X. Comparing response rates from web and mail surveys: a meta-analysis. Field Methods. 2008;20(3):249-271. doi:10.1177/ 1525822X08317085.
34. Horn PSV, Green KE, Martinussen M. Survey response rates and survey administration in counseling and clinical psychology: a meta-analysis. Educ Psychol Meas. 2009;69(3):389-403. doi:10.1177/0013164408324462.
38. Kroenke K. Efficacy of treatment for somatoform disorders: a review of randomized controlled trials. Psychosom Med. 2007;69(9):881-888. doi:10.1097/ PSY.0b013e31815b00c4.
35. Copay AG, Subach BR, Glassman SD, Polly DW Jr, Schuler TC. Understanding the minimum clinically important difference: a review of concepts and methods. Spine J. 2007;7(5):541-546. doi:10.1016/j.spinee.2007.01.008.
39. Henningsen P, Zipfel S, Herzog W. Management of functional somatic syndromes. Lancet. 2007;369(9565):946-955. doi:10.1016/S01406736(07)60159-7.
36. Löwe B, Spitzer RL, Gräfe K, et al. Comparative validity of three screening questionnaires for DSM-IV depressive disorders and physicians’ diagnoses. J Affect Disord. 2004;78(2):131-140.
40. Klinkman MS. Competing demands in psychosocial care: a model for the identification and treatment of depressive disorders in primary care. Gen Hosp Psychiatry. 1997;19(2):98-111. doi:10.1016/S0163-8343(96)00145-4.
37. Jackson JL, O’Malley PG, Kroenke K. Antidepressants and cognitive-behavioral therapy for symptom syndromes. CNS Spectr. 2006;11(3):212-222.
Invited Commentary
Assessing Somatic Symptoms in Clinical Practice Arthur J. Barsky, MD
The interesting study by Gierk et al1 tests the psychometric properties of a brief, self-report somatic symptom inventory and raises several broader questions about the sources of somatic symptoms and the use of symptom inventories in clinical practice. As the authors point out, routine clinical asRelated article page 399 sessment of somatic symptoms has many functions: although obviously serving as guideposts to aid in diagnosis, they are also important in their own right as indexes of suffering and distress and can be used to assess the effectiveness of treatment over time. Somatic symptoms are a complex and multidetermined phenomenon, and they do not bear a fixed, one-to-one relationship with medical morbidity. Their close association with psychiatric disorders, particularly anxiety and depressive disorder, is well established and has been confirmed again in this study. Thus, Gierk and colleagues found that somatic symptoms were more highly correlated with anxiety and depression than with self-reported general health. Therefore, it should not be surprising that there is a substantial body of psychiatric literature on the prevalence, incidence, and nature of somatic symptoms as concomitants of psychiatric disorder. The Somatic Symptom Scale–8 (SSS-8) used in this study is derived from the Patient Health Questionnaire–15, a somatization scale that was developed to assess the somatic symptoms that frequently accompany psychiatric disorders rather than serious medical diseases, that is, to assess somatization rather than medical morbidity. The component items of the SSS-8, therefore, are closely associated with psychiatric distress, medically unexplained symptoms, and diagnosable somatoform disorders. This close association of somatic symptoms w ith psychiatric disorders is one reason that approximately one-third of the symptoms reported by patients in primary care and specialty medical settings remain jamainternalmedicine.com
medically unexplained after adequate evaluation.2 This of course does not invalidate their use in the general medical setting but does underscore the fact that they are tapping psychiatric disorder as much as medical disorder. The lack of a one-to-one relationship between somatic symptoms and medical morbidity is also apparent in the enormous interindividual variability seen in the symptoms of patients with the same severity and extent of medical disease. This has been documented in conditions as diverse as degenerative disk disease, coronary artery disease, asthma, anemia, diabetes mellitus, cholelithiasis, insomnia, and benign prostatic hypertrophy. Even when significant medical disease is present, patients’ symptoms may nonetheless be unrelated to their disease, the association being coincidental rather than causal. Symptoms that appear to be disease specific may not in fact be caused by the ostensible disease.3 When putative disease-specific symptoms (eg, headache and fatigue) have high base rates in the general population and the disease is common (eg, hypertension), the symptoms and disease are likely to occur concomitantly on a statistical basis alone.4 Somatic symptoms can even result from learning for the first time that one has a medical condition that was previously asymptomatic. Thus, receiving the initial diagnosis of hypertension is associated with the onset of symptoms commonly assumed to be caused by hypertension (eg, headache, dizziness, weakness, and epistaxis), even after controlling for the initiation of antihypertensive therapy.5 To add to the complexity of the phenomenology of somatic symptoms, epidemiologic surveys of ostensibly healthy nonpatient populations reveal that bothersome symptoms are prevalent among people with no serious medical and psychiatric disorders.6 As many as 80% to 90% of adults experience at least 1 symptom every 1 to 3 weeks,7and only 19% to 27% of people report having had no symptoms in the previous 3 days.8 Thus, 14% to 45% of American adults report being bothered JAMA Internal Medicine March 2014 Volume 174, Number 3
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archinte.jamanetwork.com/ by a University of Birmingham User on 05/31/2015
407
Research Original Investigation
The Somatic Symptom Scale–8
by headache, 19% to 39% report fatigue, 32% to 50% report back pain, and 5% to 23% report dizziness. All of this information provides a broader context for considering the study by Gierk et al. First, the survey was conducted in a community-dwelling sample—not a medical one— and the relationship between their symptoms and those of patients encountered in medical practice requires further investigation, as the authors emphasize. These differences might be quite substantial, which is suggested by the very low scores reported by the respondents (mean, 3.23, on a scale with a maximum score of 32). In addition, the medical significance of the symptoms that were reported is unclear. They may well represent the transient dysfunctions and benign, self-limited ailments that are an endemic reservoir of distress inherent in daily life rather than reflect serious medical or psychiatric morbidity. In this sense, the symptoms reported by the communitydwelling survey participants likely differ substantially from the symptoms reported by medical patients. The study also raises interesting questions about the natural history of the symptoms reported. The investigators chose to ask about current (in the past week) symptoms. It will be important in future work to determine how transient such symptoms are. There is a clinical aphorism that 90% of symptoms that on initial presentation have no clear medical basis will be transient and self-limited, subsiding within 2 weeks. The validity of this adage needs to be tested. The authors have gone a considerable distance in demonstrating the internal reliability and convergent and concurrent validity of their scale, for example, finding it significantly associated with self-reported use of medical care. Future work will need to examine this association more closely using objective measures of medical care use, since patient recall over periods as long as 1 year is generally inaccurate and unreliARTICLE INFORMATION Author Affiliations: Department of Psychiatry, Brigham and Women’s Hospital, Boston, Massachusetts; Department of Psychiatry, Harvard Medical School, Boston, Massachusetts. Corresponding Author: Arthur J. Barsky, MD, Department of Psychiatry, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115 (abarsky @partners.org). Published Online: November 25, 2013. doi:10.1001/jamainternmed.2013.12177. Conflict of Interest Disclosures: None reported. REFERENCES 1. Gierk B, Kohlmann S, Kroenke K, et al. The Somatic Symptom Scale–8 (SSS-8): a brief measure
408
able. The relationship between symptoms and medical helpseeking is of particular interest at the ends of the spectrum: stoical and underserved populations who endure substantial distress and significant disease without seeking medical attention at one extreme and, at the opposite end of the spectrum, those who visit physicians repeatedly in the absence of significant medical or psychiatric morbidity. As concerns about the costs of care rise, we need to know much more about the ways in which people act or do not act on their symptoms. It will likewise be important in future work to examine the association between these somatic symptoms and objective measures of medical morbidity. Self-reported physical health is not necessarily closely correlated with objective measures of health status as assessed with a medical record audit or a physician rating. Obviously, such case-by-case assessment of medical morbidity is not possible in a large population-based survey such as this one. In addition, computerized methods of indexing aggregate medical morbidity from the medical records or pharmacy records are difficult to develop. Although the relationship between somatic symptoms and medical morbidity is complex and fickle, none of this undermines the importance of symptoms in and of themselves, regardless of their source. They are a source of suffering and distress and thus a critical objective of all medical care. The absence of a serious medical cause for some symptoms in no way invalidates or delegitimizes them. Integration of the SSS-8 into routine, measurementbased care would constitute a substantial advance. An instrument with excellent psychometric properties like those of the SSS-8 is necessary for research to further our understanding of the phenomenology, epidemiology, natural history, and treatment response of somatic symptoms.
of somatic symptom burden [published online November 25, 2013]. JAMA Intern Med. doi:10.1001/jamainternmed.2013.12179.
5. Alderman MH, Lamport B. Labelling of hypertensives: a review of the data. J Clin Epidemiol. 1990;43(2):195-200.
2. Kroenke K. Patients presenting with somatic complaints: epidemiology, psychiatric comorbidity and management. Int J Methods Psychiatr Res. 2003;12(1):34-43.
6. Kroenke K, Price RK. Symptoms in the community: prevalence, classification, and psychiatric comorbidity. Arch Intern Med. 1993;153(21):2474-2480.
3. Kroenke K. Studying symptoms: sampling and measurement issues. Ann Intern Med. 2001;134(9, pt 2):844-853.
7. White KL, Williams TF, Greenberg BG. The ecology of medical care. N Engl J Med. 1961;265:885-892.
4. Novy D, Berry MP, Palmer JL, Mensing C, Willey J, Bruera E. Somatic symptoms in patients with chronic non–cancer-related and cancer-related pain. J Pain Symptom Manage. 2005;29(6): 603-612.
8. Khosla PP, Bajaj VK, Sharma G, Mishra KC. Background noise in healthy volunteers—a consideration in adverse drug reaction studies. Indian J Physiol Pharmacol. 1992;36(4):259-262.
JAMA Internal Medicine March 2014 Volume 174, Number 3
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archinte.jamanetwork.com/ by a University of Birmingham User on 05/31/2015
jamainternalmedicine.com
