Introduction A low ferritin in the setting of microcytic anaemia is both sensitive and specific for iron deficiency anaemia (IDA) but its role in normocytic anaemia is unclear. Many laboratories do not offer ferritin testing in normocytic anaemia. We have investigated the prevalence of microcytic and normocytic anaemia in patients presenting with upper and lower gastrointestinal (GI) cancer and assessed the cost-benefit of ferritin in models of microcytic and normocytic anaemia.
Methods Two decision-analysis models were created to evaluate a hypothetical cohort of postmenopausal women and men with microcytic anaemia. Two strategies were investigated for each type of anaemia: microcytic – ferritin and GI endoscopy (gastroscopy, D2 biopsy and colonoscopy) if IDA or no ferritin and GI endoscopy for all; normocytic—ferritin and GI endoscopy if IDA or no ferritin and no GI endoscopy. A ferritin level <20 μg/ml was used to determine iron deficiency. Baseline prevalence variables were obtained after a literature search. Records of patients with upper and lower gastrointestinal cancers at our hospital in the last year were audited to determine the prevalence and type of anaemia. Costs of endoscopic procedures were derived from HRG tariffs. Costs for advanced cancer were obtained from published literature. Monte-Carlo and sensitivity analysis were carried out.
Results Of 75 upper GI cancers, 51 (68%) were anaemic on presentation (82% normocytic, 18% microcytic). Of 75 lower GI cancers, 59 (79%) were anaemic (75% normocytic, 25% microcytic). The average cost of evaluating a patient with microcytic anaemia when ferritin was used was £1106, compared to £1526 when not, yielding a cost-saving of £420 per patient. With normocytic anaemia, the average cost of investigation was £223 per patient when ferritin was used to determine further investigations compared to £243 per patient when not, yielding a cost-difference of £20 per patient. This difference was due to a number of cancers presenting late in the arm where ferritin was not used to determine IDA. Monte Carlo simulation and sensitivity analysis on cost of ferritin showed a consistent cost-difference in favour of using ferritin in microcytic anaemia for a cost per test from £5 to £15. In normocytic anaemia, the percentage presenting at an inoperable stage of GI malignancy was critical in determining whether ferritin was cost-effective. So long as at least 40% of GI cancers were inoperable, ferritin was cost-effective in normocytic anaemia.
Conclusion Ferritin is associated with cost-savings in the investigation of suspected IDA and should be used as a baseline investigation in planning endoscopic investigations. It has clear value in microcytic anaemia and is marginally cost-effective in normocytic anaemia, where it is dependent on the rate of GI cancers in patients with IDA with normocytic anaemia and how many are inoperable.
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