Physician global assessments or blood tests do not predict mucosal disease activity in ulcerative colitis

BACKGROUND: Mucosal healing has been proposed as the therapeutic end point in the treatment of patients with ulcerative colitis (UC). OBJECTIVE: To investigate the relationship between physician global assessment (PGA) and laboratory blood tests (complete blood count, ferritin, C-reactive protein, albumin) and endoscopic findings in UC to determine whether they could be adequate surrogates for endoscopy. METHODS: A retrospective chart review of patients known to have UC from July 2008 to November 2012 was performed at the Health Sciences Centre, Winnipeg, Manitoba. Patients included individuals with UC who underwent colonoscopy within one month of clinic assessment. Blood tests were standard at the time of colonoscopy. Patients presenting through the emergency department, those with colonoscopies performed outside the authors' institution, or whose colonoscopies and clinical assessments were undertaken more than one month apart were excluded. The PGA was used to determine disease activity in patients before colonoscopy. The Ulcerative Colitis Endoscopic Index of Severity, a validated scoring system to rate endoscopic disease severity in ulcerative colitis, was adapted. RESULTS: A total of 154 patients (mean [+/- SD] age 44 +/- 15.7 years) with UC were identified including 82 (53%) men. Mean hemoglobin level was 139 g/L, mean platelet level was 296x10(9)/L, mean ferritin level was 102 mu g/L, mean C-reactive protein level was 10 mg/L and mean albumin level was 40 g/L. Using endoscopy as the 'gold standard' for assessing UC activity (moderate-severe), abnormalities in laboratory parameters and PGA were both highly specific but not sensitive for identifying individuals with at least moderately active endoscopic disease. The PGA had higher positive and negative predictive values than the laboratory parameters. CONCLUSION: Neither blood tests nor PGA could replace endoscopy for assessing mucosal healing. When patients experienced active symptoms and abnormal serum markers, they were highly likely to have abnormal endoscopy. However, inactive symptoms or normal laboratory values did not preclude having active endoscopic disease.