• BACKGROUND
    • Physicians often diagnose diverticulitis and prescribe antibiotics in outpatients with abdominal pain and tenderness without other evidence.
  • AIM
    • We investigated the misattribution of irritable bowel syndrome (IBS) symptoms to diverticulitis in outpatients.
  • METHODS
    • In patients diagnosed with diverticulitis and dispensed antibiotics in an integrated healthcare system, we retrospectively compared 15,846 outpatients managed without computed tomography (CT) versus 3750 emergency department/inpatients who had CT. We assessed demographics and past history, including 17 symptom-based somatic and 11 mental disorders and three somatic-mental comorbidity pairs (dyads) coded over 3 years and seven drug classes dispensed over 1 year before diagnosis.
  • RESULTS
    • Univariate analysis showed small intergroup demographic differences. Outpatients had increases in prior diverticulitis, including outpatient-managed episodes, total somatic diagnoses (p < .0001), eight somatic and three mental disorders (p ≤ .015), all three dyads (p ≤ .05), and dispensing of three drug classes (p ≤ .016). IBS had been diagnosed in 2399 (15.1 %) outpatients versus 361 (9.6 %) emergency department/inpatients (p < .0001), the greatest increase in any comorbidity. Emergency department/inpatients had no somatic comorbidity more often but more alcohol dependence, non-dependent drug abuse, and opioid dispensing (p ≤ .05). Regression analysis revealed outpatient care was independently positively associated with younger age, non-Hispanic white race/ethnicity, less Charlson comorbidity, diverticulitis history, IBS, chest pain, dyspepsia, fibromyalgia, low back pain, migraine, acute reaction to stress, and antispasmodic and anxiolytic dispensing and negatively associated with non-dependent drug abuse and opioid dispensing (p ≤ .0226).
  • CONCLUSIONS
    • Multiple types of indirect and concordant evidence suggest misattribution of IBS pain to diverticulitis and unnecessary antibiotic therapy in outpatients.