Anemia and idiopathic intracranial hypertension: a retrospective observational and case-control study

Authors: Irina Sverdlichenko, Caberry W. Yu, Edward Margolin, Jonathan A. Micieli. 
Author Disclosure Block: I. Sverdlichenko: None. C.W. Yu: None. E. Margolin: None. J.A. Micieli: None.

Purpose: The relationship between anemia and idiopathic intracranial hypertension (IIH) continues to be controversial. The goal of the present study was to: 1) Determine the relative prevalence of anemia in IIH patients compared to age and sex-matched controls attending neuro-ophthalmology clinics and 2) To compare the initial and final visual outcomes of IIH patients with and without anemia. 

Study Design: Retrospective observational and case-control study. 

Methods: 123 consecutive IIH patients were recruited from tertiary neuro-ophthalmology clinics and matched by age and sex to 113 non-IIH neuro-ophthalmology controls. Retrospective chart review obtained information on demographics, symptoms and visual function at presentation and final follow-up. Complete blood counts (CBC) were collected within 6 months of diagnosis and 3 months of final follow-up and anemia diagnosis was made based on hemoglobin <120g/L for women and <130g/L for men. Anemia was further classified as mild (hemoglobin >110g/L), moderate (hemoglobin 80-109g/L), and severe (hemoglobin <80g/L); as well as microcytic (mean corpuscular volume (MCV) <80fL), normocytic (MCV 80-100fL) and macrocytic (MCV>100fL). 

Results: More IIH patients than controls met criteria for anemia (22.8%, 28/123 versus 10.6%, 12/113, p=0.01), with an odds ratio of 2.48 (95% CI 1.19-5.16). IIH patients had a significantly lower mean hemoglobin than controls (127.6 ± 18.0g/L versus 133.0 ± 11.8g/L, p<0.01) and 17.9% (5/28) of anemic IIH patients had severe anemia compared to zero in the control group. When comparing the 28 IIH patients with anemia to the 95 IIH patients without anemia, there were no differences between groups in terms of sex, age, body mass index (BMI) or symptomatology. IIH patients with anemia were more likely to have mild-to-moderate visual acuity impairment (logMAR 0.3-1, 14.3% versus 3.7%, p=0.01) and worse Humphrey mean deviation (-5.7dB + 8.1 versus -3.4dB + 4.2, p=0.048) compared to non-anemia IIH patients at presentation. At final follow-up, there was no difference in visual acuity, but Humphrey mean deviation continued to be worse among anemic IIH patients (-5.7 + 8.1 versus 3.4 + 4.2, p=0.048) even when controlling for age, sex, and BMI.

Conclusions: Anemia is more prevalent among IIH patients compared to neuro-ophthalmology controls and may influence the initial and final visual function in IIH patients. As a CBC is a widely available test, we suggest that this test be obtained in all patients with new papilledema.