Fig. 1.

Flowchart showing analysis sets to conduct a fact-finding survey for HAM/TSP. The entire analysis set in this study consisted of 486 patients enrolled sequentially in the HAM/TSP patient registry “HAM-net” from March 2012 to December 2016. All 486 patients received an initial telephone interview just after registration (a). Information obtained from this interview was considered as baseline. Subsequently, we conducted annual interviews. We regarded the 434 patients who received an annual interview for two consecutive years as a one-year observation group (b). Likewise, we considered the 370 patients interviewed annually for three consecutive years as a two-year observation group (c). The three-year observation and the four-year observation groups consisted of 304 (d) and 257 patients (e), respectively. See Methods for details