BackgroundThe French Renal Epidemiology and Information Network (REIN) registry collect dialysis initiation context for each patient starting dialysis with a flawed definition of urgent start dialysis (USD). The main objective of this study was to identify factors associated with USD in patients regularly followed-up by a nephrologist using a classification of USD considering the preparation to renal replacement therapy.MethodsThis retrospective cohort study included adult patients who started dialysis between 2012 and 2018 in the Franche-Comté region of France after a minimum of two nephrology consultations. We classified dialysis initiation context as follows: USD for patients with no dialysis access (DA) created or planned, unplanned non urgent start dialysis (UNUSD) for patients starting with a recent or non-functional DA and planned start dialysis (PSD) for those starting with a functional and mature DA.ResultsFour hundred and sixty-five patients met inclusion criteria. According to REIN registry, 94 (20.3%) patients were urgent starters (US) whereas with our classification 80 (17.2%) and 73 (15.7%) where respectively US and unplanned non urgent starters (UNUS). The factors independently associated with USD in our classification were: stroke (odds ratio(OR) = 2.76, 95% confidence interval (95%CI)=[1.41–5.43]), cardiac failure (OR = 1.78, 95%CI=[1.07–2.96]) and the number of nephrology consultations prior dialysis onset (OR = 0.73, 95%CI=[0.64–0.83]). Thirty-one patients died during the first year after dialysis start. According to our classification, we observed significantly different survival probabilities: 95.7%, 89.5% and 83.4% respectively for planned starters, UNUS and US (p = 0.001).ConclusionThe two factors independently associated with USD were cardiac failure and stroke.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12882-023-03222-1.