The PHQ-12 Somatic Symptom scale as a predictor of symptom severity and consulting behaviour in patients with irritable bowel syndrome and symptomatic diverticular disease

BACKGROUND Anxiety, depression and non-gastrointestinal symptoms are often prominent in IBS but their relative valuein patient management has not been quantitatively assessed. We modified the Patient Health Questionnaire15 (PHQ-15) by excluding the 3 gastrointestinal items to create the PHQ-12 Somatic Symptom scale (PHQ-12 SS). AIMS To compare the value of the PHQ-12 SS scale to the Hospital Anxiety and Depression (HAD) scale in predicting symptoms and patient behaviour in IBS and diverticular disease. METHODS: We compared 151 healthy volunteers (HV), 319 IBS patients and 296 patients with diverticular disease(DD), 113 asymptomatic [ASYMPDD] and 173 symptomatic DD (SYMPDD). RESULTS: PHQ-12 SS scores for IBS and SYMPDD were significantly higher than HV. Receiver-operator curves showed a PHQ-12 SS >6 gave a sensitivity for IBS of 66.4% with a specificity of 94.7% and a Positive Likelihood Ratio (PLR) = 13.2, significantly better than that associated with an HAD anxiety score >7, PLR = 3.0 and depression score >7 PLR = 6.5. PHQ-12 SS correlated strongly with IBS severity scale (IBSSS) and GP visits in both IBS and DD. CONCLUSION: The PHQ-12 SS scale is a useful clinical tool which correlates with patient behaviour in both IBS and SYMDD.