Patients with non-Jo-1 anti-RNA-synthetase autoantibodies have worse survival than Jo-1 positive patients
We read with interest the manuscript by Aggarwal et al. entitled “Patients with non-Jo-1 anti-RNA-synthetase autoantibodies have worse survival than Jo-1 positive patients” 1. This large cohort study provides important information on outcomes for patients with antisynthetase syndrome (ASS), based on the specificity of the anti-RNA-synthetase autoantibody subtypes. Interestingly, the authors decided to include patients with anti-EJ, OJ and KS -tRNA-synthetase autoantibodies, something which had not yet been done in the previous studies2,3, due to the rarity of these autoantibodies. The conclusion by Aggarwal et al. confirmed our previous data showing a worse prognosis for non-Jo-1 patients as compared with Jo-1 patients2. However, this study prompts questions on the two following points:
1. The authors showed that a longer delay in diagnosing non-Jo1 patients was a major predictor of poor survival. For this, they used a multivariate Cox model analysis, adjusted for diagnosis delay, as well as for the following parameters: gender, ethnicity, age at initial and final diagnosis. However, the model was not tested with any of the variables that have clearly been shown to correlate with either poor prognosis (i.e. interstitial lung disease1 and pulmonary hypertension1,4) or with better survival (i.e. the presence of a myositis at ASS diagnosis2). Although the main objective is of course to decrease the diagnosis delay in all patients, it would be quite valuable to know whether this delay is an independent predictor of survival after adjusting for these variables.
2. The results shown in Table 3 and in Figure 1 are difficult to interpret since no information is provided about the censored data (overall median patient follow-up <3 years vs survival evaluations >5 years). In Table 3, the absolute number of patients evaluated at 5 and 10 years is not given, which leads to some confusion: do the percentages of patients correspond to the ratio of living patients to total number of patients at diagnosis, or to the probability of survival, as estimated with the Kaplan-Meyer method? Similarly, there are no marks to help identify the censored data in the Kaplan-Meyer curve of Figure 1, making it difficult to identify the number of censored patients during the follow-up period.
We thank the authors for addressing these issues and for providing additional data that will be useful for understanding the factors associated with survival of patients with ASS.
1. Aggarwal R, Cassidy E, Fertig N, et al. Patients with non-Jo-1 anti-tRNA-synthetase autoantibodies have worse survival than Jo-1 positive patients. Ann Rheum Dis 2013 Feb 26. [Epub ahead of print] PubMed PMID: 23422076.
2. Hervier B, Devilliers H, Stanciu R, et al. Hierarchical cluster and survival analyses of antisynthetase syndrome: phenotype and outcome are correlated with anti-tRNA synthetase antibody specificity. Autoimmun Rev 2012;12:210-7 .
3. Marie I, Josse S, Decaux O, et al. Comparison of long-term outcome between anti-Jo1- and anti-PL7/PL12 positive patients with antisynthetase syndrome. Autoimmun Rev 2012;11:739-45.
4. Hervier B, Meyer A, Dieval C, et al. Pulmonary hypertension in antisynthetase syndrome: prevalence, etiology and survival. Eur Respir J 2013 Feb 8. [Epub ahead of print] PubMed PMID: 23397301.
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