25.2 out of 33 is quite high (i.e. very positive results). In fact, those results seem too good to be true, and are likely due to the limitations of the study. In particular, by 54 months of treatment the non-responders or those with side effects would have already stopped taking thyroxine. Nonetheless, the data is consistent with other studies indicating that supraphysiological doses of levothyroxine has few and mild side effects (regardless of the sample population).