Background: Diverticulitis is considered common in the outpatient population, with mild variants of described diagnostic criteria: left lower quadrant pain, fever, and leukocytosis. Here, expected criteria utilization among outpatients with a possible diagnosis of diverticulitis is assessed.
Study design: Primary care acute clinic visits in 2008 for diverticulitis (ICD-9 562.11/562.13) or left lower quadrant pain (789.04) were identified among patients ≥ 40 years old. Encounters were reviewed through structured manual chart abstraction and evaluated for diagnostic accuracy compared to expected criteria. Analysis included inter-rater reliability (kappa tests) and descriptive frequencies by diagnosis code and diverticulitis rating (χ (2) tests).
Results: A total of 376 acute visits were identified with codes for diverticulitis (n=97) or left lower quadrant pain (n=279). High inter-rater reliability was demonstrated for key clinical variables (kappa=0.84-1.0). Left lower quadrant pain was reported in >75% of patients, while temperature and white blood cell count data were frequently unavailable. Lack of these expected criteria resulted in low diagnostic accuracy ratings ("No/unlikely"-53.6% diverticulitis, 88.2% left lower quadrant pain, p<0.001).
Conclusions: This investigation raises concern for low accuracy in the outpatient diagnosis of diverticulitis due to inconsistent use of expected criteria, suggesting a smaller population with true diverticulitis than previously anticipated, or lack of criteria applicability in this setting.