Incidence of Serious Infections among Patients with ALS in a U.S. Health Insurance Claims Database (P07.086)

OBJECTIVE: This study estimated the risk of serious infections in patients with ALS compared to controls in the i3 InVision Data Mart Multiplan database. BACKGROUND: Respiratory infections are common in ALS. Literature on other types of infections in patients with ALS is limited. DESIGN/METHODS: Two cohorts of patients ≥ 18 years of age were included in this analysis: ALS patients (any patient with 1 inpatient or 2 outpatient medical claims containing ICD-9 code 335.20) and controls (n=65,000 randomly selected patients with no medical claims for ALS or other motor neuron diseases). Serious infections (bacteremia, cellulitis, encephalitis, endocarditis, meningitis, pneumonia, and pyelonephritis) were selected and defined using previously validated medical claims algorithms and inpatient claims. After excluding patients with previous history of an outcome within 60 days of the index date, each analysis included 65,000 controls and approximately 3260 ALS patients (min=3256, max=3265). Poisson regression was used to calculate incidence rates while Cox proportional hazards models were used to calculate hazard ratios (HR). RESULTS: Age- and gender-adjusted incidence rates in ALS and controls, respectively (per 100,000 person-years): bacteremia 392.48 and 44.48; cellulitis 143.36 and 78.36; pneumonia 303.95 and 7.54; and pyelonephritis 68.41 and 15.07. Age- and gender-adjusted HRs in patients with ALS: bacteremia 8.7 (95% CI: 5.1, 14.8); cellulitis 1.8 (95% CI: 0.9, 3.4); pneumonia 39.8 (95% CI: 12.9, 123.2); and pyelonephritis 4.5 (95% CI: 1.0, 19.3). No cases of encephalitis, endocarditis, or meningitis were identified in ALS patients. Further results for other infections will be presented at conference. CONCLUSIONS: The present analysis found an increased risk of select serious infections requiring hospitalization among ALS patients relative to the general population. Clinicians should be vigilant for signs of infection in ALS patients. Supported by: Biogen Idec. Disclosure: Dr. Williams has received personal compensation for activities with Biogen Idec as an employee. Dr. Williams holds stock and/or stock options in Biogen Idec. Dr. Kerr has received personal compensation for activities with Biogen Idec as an employee and holds stock options in Biogen. Dr. Farwell has received personal compensation for activities with Biogen Idec as an employee.