血小板数が腎臓悪液質と心血管死亡率の関連に寄与

血小板数が高いことが末期腎不全患者の腎臓悪液質と心血管死亡率の関連に寄与しているという論文を紹介します。

Molnar MZ, Streja E, Kovesdy CP, Budoff MJ, Nissenson AR, Krishnan M, Anker SD, Norris KC, Fonarow GC, Kalantar-Zadeh K: High platelet count as a link between renal cachexia and cardiovascular mortality in end-stage renal disease patients. Am J Clin Nutr. 2011 Aug 3. [Epub ahead of print]

末期腎不全患者では血小板数が高いことがしばしばあります。今回の研究では血小板数が30万以上の場合、心血管死亡率が高いという仮説を検証しています。

結果として血小板数が15－20万の患者と比較して、30‐35万、35－40万、40万以上の患者では総死亡率と心血管死亡率がそれぞれ6%(7%), 17%(15%), 24%(25%) 高いという結果でした。

仮説ですが末期腎不全による悪液質で炎症が持続する結果、血小板数が増えて、血栓症を起こしやすい可能性があります。また血小板数が高い患者は、より炎症が高度で全身状態が不良になりやすいために死亡率が高い可能性があります。悪液質の患者では血小板数も気にしたほうがよいかもしれません。

Abstract

BACKGROUND:
It is not clear why cardiac or renal cachexia in chronic diseases is associated with poor cardiovascular outcomes. Platelet reactivity predisposes to thromboembolic events in the setting of atherosclerotic cardiovascular disease, which is often present in patients with end-stage renal disease (ESRD).

OBJECTIVES:
We hypothesized that ESRD patients with relative thrombocytosis (platelet count >300 × 10(3)/μL) have a higher mortality rate and that this association may be related to malnutrition-inflammation cachexia syndrome (MICS).

DESIGN:
We examined the associations of 3-mo-averaged platelet counts with markers of MICS and 6-y all-cause and cardiovascular mortality (2001-2007) in a cohort of 40,797 patients who were receiving maintenance hemodialysis.

RESULTS:
The patients comprised 46% women and 34% African Americans, and 46% of the patients had diabetes. The 3-mo-averaged platelet count was 229 ± 78 × 10(3)/μL. In unadjusted and case-mix adjusted models, lower values of albumin, creatinine, protein intake, hemoglobin, and dialysis dose and a higher erythropoietin dose were associated with a higher platelet count. Compared with patients with a platelet count of between 150 and 200 × 10(3)/μL (reference), the all-cause (and cardiovascular) mortality rate with platelet counts between 300 and <350, between 350 and <400, and ≥400 ×10(3)/μL were 6% (and 7%), 17% (and 15%), and 24% (and 25%) higher (P < 0.05), respectively. The associations persisted after control for case-mix adjustment, but adjustment for MICS abolished them.

CONCLUSIONS:
Relative thrombocytosis is associated with a worse MICS profile, a lower dialysis dose, and higher all-cause and cardiovascular disease death risk in hemodialysis patients; and its all-cause and cardiovascular mortality predictability is accounted for by MICS. The role of platelet activation in cachexia-associated mortality warrants additional studies.