Systematic Review of Prognostic Factors for Mortality in Dogs with Immune‐mediated Hemolytic Anemia

BACKGROUND: Treatment of dogs with primary immune‐mediated hemolytic anemia (IMHA) is difficult and frequently unrewarding. Prognostic factors have been evaluated in a number of previous studies, and identification of such factors would be beneficial to enable selection of appropriate therapeutic regimens and supportive care. OBJECTIVES: The aim of the current study was to undertake a critical appraisal of the risk of bias in evidence relating to prognostic indicators for mortality in dogs with IMHA. ANIMALS: Three hundred and eighty client‐owned dogs with spontaneous primary idiopathic IMHA reported in 6 previous studies. METHODS: A systematic review was conducted to evaluate evidence relating to prognostic factors for mortality in dogs with primary IMHA. Search tools were employed to identify articles and a validated appraisal tool was used to assess the quality of individual studies by considering inclusion and exclusion criteria, measurement of prognostic, outcome and confounding variables, and statistical methods. RESULTS: Few studies evaluated prognostic indicators for IMHA in dogs, and all of these suffered from methodologic flaws in at least 1 major area. Fifteen different variables were identified as prognostic indicators, with 2 variables identified by >1 study. CONCLUSIONS AND CLINICAL IMPORTANCE: There are few pieces of high‐quality evidence available to enable estimation of prognosis for dogs presenting with primary IMHA.