LAUSR

We read with interest the manuscript by Wang et al. describing and validating a prognostic score for overall survival (OS) for patients with POEMS syndrome. The authors used four easily determined parameters to stratify patients with POEMS syndrome in three different risk categories. However, their study consisted exclusively of Asian patients. We sought to validate their scoring algorithm in a Caucasian-based patient population that would be more relevant to patients treated in the United States (US) and Europe. We included patients diagnosed from 15 September 1996 to 2 June 2014 with the complete data for each one of the parameters included in the scoring system. POEMS syndrome was diagnosed using previously established criteria. Definitions and scoring were identical to these used in the study by Wang et al. Systolic pulmonary arterial pressure was estimated based on duplex cardiac ultrasound, and pulmonary hypertension (PAH) was defined as systolic pulmonary arterial pressure⩾ 50 mm Hg. The estimated glomerular filtration rate (eGFR) was calculated using the CKD–EPI equation. All pleural effusions were defined radiographically. Patients were assigned one point for each of the following: age450 years, presence of PAH, presence of pleural effusions and two points for eGFRo 30 ml/min/1.73 m. Patients were then stratified into 3 risk categories according to total number of points: low (0 points), intermediate (1 point) and high (⩾2 points). Median follow-up for OS was 76 months (1–237). Statistical analyses were performed using JMP statistical software (SAS, Carey, NC, USA). OS was calculated from diagnosis and was estimated using the method of Kaplan-Meier. The log-Rank test was used to calculate OS differences between the groups. A P-value of o0.05 was considered statistically significant. Of 194 patients with POEMS syndrome, seen at the Mayo Clinic during the study period, 138 patients (71%) had the complete scoring data and were included in this study. Of 138 patients, 76 (55%) were older than 50, 24 (17%) had PAH, 29 (21%) had pleural effusions and 7 (5%) had an eGFRo 30 ml/min/1.73 m. Thirty patients (22%) were high risk, 62 (45%) intermediate risk and 46 (33%) low risk. Of 138 patients, 124 (90%) were Caucasian, 11 were African–American (8%) and 3 were Pacific Islanders (2%). Five and 10 year OS for each risk group was as follows: low risk-92 and 85%, respectively; intermediate risk-89 and 80%, respectively; high risk65 and 42%, respectively (Figure 1). A two-sided P-value across groups was o0.001; however, the OS between the intermediate and low-risk groups was not significantly different. In this study, we validate the prognostic score proposed by Wang et al. in a US-based population. We found that only the high-risk group offers an incremental prognostic value over the intermediate and low risk groups. There are several reasons that might explain this observation. Twenty-nine percent of patients did not have the complete data and were excluded from the study. Furthermore, pleural effusions were less prevalent in our study (21 versus 40% in the study by Wang). This might reflect a difference in disease biology between Asian and Caucasian patients as well as differences in practice patterns such as timing of correct diagnosis and treatments used prior to establishing the diagnosis of POEMS syndrome. Nonetheless, the remaining scoring characteristics as well as survival estimates are almost identical between the 2 cohorts. In summary, we have validated a prognostic system for OS in patients with POEMS syndrome and propose that this can be applied to a broader patient population.