Utility‐based outcomes made easy: The number needed per quality‐adjusted life year gained. An observational cohort study of tumor necrosis factor blockade in inflammatory arthritis from Southern Sweden

Objective To introduce a novel, simple, utility‐based outcome measure, the number needed per quality‐adjusted life year (QALY) gained (NNQ), and to apply it in clinical practice in anti–tumor necrosis factor (anti‐TNF)–treated patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and spondylarthritis (SpA). Methods The NNQ is the number of patients one has to treat in order to gain 1 QALY. It is calculated as the inverted value of the utility gain (area under the curve) over 1 year in a cohort subjected to an intervention. EuroQol Index utility data from the South Swedish Arthritis Treatment register were used. Results Patients with RA (n = 1,001), PsA (n = 241), and SpA (n = 255) were eligible for the study. First, second, and third treatment courses were studied. For RA, NNQ was 4.5, 6.4, and 5.2 for first, second, and third courses, respectively. For PsA and SpA, NNQ was 4.2–4.5, irrespective of treatment order. Treatment groups with