Background The Danish Myelodysplastic Syndromes Database (DMDSD) comprises nearly all patients diagnosed with myelodysplastic syndromes (MDS) in Denmark since 2010. The DMDSD has not yet been used for epidemiological research and the quality of registered variables remains to be investigated. Objective To describe characteristics of the patients registered in the DMDSD and to calculate predictive values and the proportion of missing values of registered data records. Methods We performed a nationwide cross-sectional validation study of recorded disease and treatment data on MDS patients during 2010–2019. Patient characteristics and the proportion of missing values were tabulated. A random sample of 12% was drawn to calculate predictive values with 95% confidence intervals (CIs) of 48 variables using information from medical records as a reference standard. Results Overall, 2284 patients were identified (median age: 76 years, men 62%). Of these, 10% had therapy-related MDS, and 6% had an antecedent hematological disease. Hemoglobin level was less than 6.2 mmol/L for 59% of patients. Within the first two years of treatment, 59% received transfusions, 35% received erythropoiesis-stimulating agents, and 15% were treated with a hypomethylating agent. For the majority of variables (around 80%), there were no missing data. A total of 260 medical records were available for validation. The positive predictive value of the MDS diagnosis was 92% (95% CI: 88–95). Predictive values ranged from 64% to 100% and exceeded 90% for 36 out of 48 variables. Stratification by year of diagnosis suggested that the positive predictive value of the MDS diagnosis improved from 88% before 2015 to 95% after. Conclusion In this study, there was a high accuracy of recorded data and a low proportion of missing data. Thus, the DMDSD serves as a valuable data source for future epidemiological studies on MDS.

Background The Danish National Patient Registry holds data on hematological procedure codes including date and type of treatment from all hematological departments in Denmark. The validity of the hematological procedure codes remains to be clarified before they are used in epidemiological research. Patients and Methods Using the Danish Myelodysplastic Syndromes Database, we identified 897 patients diagnosed with myelodysplastic syndromes or chronic myelomonocytic leukemia treated at five Danish Hospitals between 1 January 2012 and 30 April 2019. From the Danish National Patient Registry, we ascertained information about hematological procedure codes and date of procedure registered on each patient and generated random samples. Using medical record review as the reference standard, we validated procedure codes in the Danish National Patient Registry and calculated positive predictive values (PPVs) with 95% confidence intervals (CIs) for each procedure code. Results A total of 523 medical records (99% of the total sample) were available for review. PPVs for specific procedure codes ranged from 71% to 100%. The overall PPV was 91% (95% CI: 88%–92%), reflecting PPVs of 95% (95% CI: 92%–97%) for low‐dose‐chemotherapy, 90% (95% CI: 81%–96%) for high‐dose chemotherapy, 99% (95% CI: 93%–100%) for allogeneic stem cell transplantation, 75% (95% CI: 62%–85%) for immuno‐modulating agents, 80% (95% CI: 74%–85%) for growth factors, and 99% (95% CI: 99%–100%) for bone marrow examination. The accuracy of coding was consistent across geographic regions and year of registration/coding. Conclusions Hematological procedure codes reported to the Danish National Patient Registry had high PPVs and are suitable for epidemiological research.

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Low socioeconomic position (SEP) may be associated with adverse outcomes in patients with myelodysplastic syndromes (MDS) inherent to for example, delayed diagnosis or reduced treatment intensity, but firm evidence is limited. In this study, we examined the association between SEP and clinical outcomes. We conducted a population-based cohort study (2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) of 2233 Danish patients with MDS.SEP measures included individual-level information on education, cohabitation status and income retrieved from Statistics Denmark. Associations between SEP measures and disease severity at diagnosis were examined using binomial regression analysis. Using time-to-event analysis, we examined the association between SEP measures and treatment with allogeneic stem cell transplantation (allo-HSCT), risk of progression to acute myeloid leukemia (AML), and death. Estimates were adjusted for covariates selected based on direct acyclic graphs and reported with 95% confidence intervals. Patients with a short education were more likely to be transfusion-dependent at diagnosis (RR = 1.25, 95% CI: 1.04-1.45) and more likely to be diagnosed with higher risk MDS according to the International Prognostic Scoring System (RR = 1.29, 95% CI: 1.03-1.62), than patients with a long education.We found no clear association between SEP and risk of progression to AML. In adjusted models, the 1-year risk of dying was higher in patients with short versus long education (RR = 1.34, 95% CI: 1.08-1.65), in patients with low versus high income (RR = 1.42, 95% CI: 1.14-1.77), and among patients who lived alone compared to those who lived with a partner (RR = 1.15, 0.98-1.35). These associations persisted after 3 years and 5 years of follow-up. Notably, patients with a short education had a markedly lower rate of undergoing treatment with allo-HSCT compared to patients with a long education (HR = 0.51, 95% CI: 0.31-0.84). In conclusion, low SEP and especially short education, were poor prognostic factors for adverse clinical outcomes among patients with MDS.

Background: Five-year overall survival for patients with myelodysplastic syndromes (MDS) is around 30%. Adverse prognostic factors include advancing age, higher blast cell percentage, poor risk cytogenetics, two or more cytopenias, high burden of comorbidity, and transfusion-dependency. The impact of socioeconomic position on clinical outcomes in MDS patients is however unclear. In this nationwide population-based cohort-study, we therefore examined the associations between the individual-level socioeconomic markers education level, cohabitation status, and income, and the risk of progression to acute myeloid leukemia (AML), and all-cause mortality among MDS patients. Methods: Using the Danish Myelodysplastic Syndromes Database, we identified all patients with incident MDS diagnosed between January 1st 2010 and December 31th 2018. The database holds valid and detailed patient- and disease-characteristics on all Danish MDS patients diagnosed since 2010. We linked the study-population with individual-level information on education, cohabitation status, income, comorbidity, progression to AML, and vital status retrieved from high-quality Danish population-based registries. We computed absolute risks of progression to AML and all-cause mortality using the cumulative incidence (risk) function accounting for death as competing risk when AML was the outcome. Also, 1-year, 3-year, and 5-year relative risks (RRs) of progression to AML and death were computed using the pseudovalue approach. All results were given crude and adjusted for age, sex, socioeconomic position (SEP), comorbidity and subtype of MDS according to the "International Prognostic Scoring System" (IPSS) and with 95% confidence intervals (CIs). Results: The final cohort comprised 2233 MDS patients (median age 75 years, 63% males). Median follow-up time was 1.7 years. The 1-year risks of progression to AML was similar across education levels (long education (>13 years): 5%, medium education (9-12 years): 6%, short education (<9 years): 6%. In adjusted models, there were no associations between education, income or cohabitation status and risk of progression to AML (Table 1). Still, patients with a short education had higher 1-year all-cause mortality (33%) compared to those with medium (22%) and longer education (21%) (Figure 1). In adjusted models the risk of death one year from diagnosis was higher in patients with short vs. longer education [RR=1.26 (95% CI: 1.03-1.55)], in patients with lower vs. higher income [RR=1.43 (95% CI: 1.17-1.75)], and among patients who were living alone compared to those who lived with someone [RR=1.19 (1.02-1.39)]. The increased risk of death among patients with short education, low income, and those who lived alone persisted after 3-year and 5-years of follow-up (Table 1). Conclusion: In a real world setting, shorter education, living alone, and lower income were not associated with increased risk of progression to AML but with inferior survival in Danish MDS patients. These results suggest that in spite of "free and equal access" to healthcare and cancer treatment in Denmark, short education, living alone, and low income are adverse prognostic factors for patients with MDS. Further analyses are ongoing to get insight into the mechanisms driving these socioeconomic disparities in MDS patients. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.