Letter and Reply

Sir, González-Espinoza et al. [1] reported that pentoxifylline (PTX) progressively and significantly reduced serum levels of tumor necrosis factor-α, interleukin-6 and C-reactive protein in the hemodialysis (HD) patients. They further concluded that PTX could be a promising agent to reduce the systemic inflammation in patients with endstage renal disease on HD. However, we have concerns about those interpretations. First, the reduced serum level of inflammation markers should not be attributed exclusively to PTX. Two other factors may also be contributing to this. (i) The baseline values of inflammation markers may be a factor. In HD patients without any clinical interference, higher initial values are often followed with a deceasing trend, lower ones with an increasing trend [2]. Therefore, with significantly higher initial baseline values in the PTX group, the reported decrease in inflammation markers might simply reflect this beginning bias. (ii) The effect of dialysis adequacy may also be a factor. In HD patients, when the dialysis is adequate, the impaired function of monocytes tends to improve, indicated by the increased level of cytokines [3]. When dialysis is not adequate, the functions of monocytes are less likely to recover, which further leads to a decreased level of inflammation markers. In González-Espinoza’s paper, the value of equilibrated Kt/Vurea was significantly higher in the control group. Also, the values of serum urea and creatinine were lower than those in the PTX-treated group. The subjects in the PTX-treated group may not have dialysis adequacy. Second, the reduced levels of inflammation markers may not indicate improved inflammation in HD patients. When the inflammation is improved in HD patients, the response to erythropoietin treatment increases with a higher level of hemoglobin [4]. However, in GoznalezEspinoze’s paper, the Hb value decreased with the values of inflammation markers also decreasing. Considering the initial inequality between the placebo and PTX group and the contradicting finding about Hb, a more conservative conclusion would be better.