Association of Platelet Counts with Outcome of ICU Stay

Abstract

Background: Low platelet count is common in intensive care unit (ICU). Thrombocytopenia has also been associated with poor outcome in ICU.1-4 There is sketchy data regarding thrombocytopenia and its effect on outcome from ICUs in India.5 We aimed to study association of platelet counts with outcome of ICU stay. Subjects and Methods: This was a retrospective study. This study was carried out in patients admitted with a diagnosis of sepsis in the medical ICU, Sepsis was defined using the criteria laid down in the surviving sepsis guidelines 2012.6 Data regarding demography (age and sex), probable source of sepsis, platelet count at admission (Plat-adm), lowest platelet count during the ICU stay (Plat-nadir), platelet fall- defined as Plat-adm Plat-nadir, APACHE-II score and SOFA score at admission were recorded. Outcome parameters were mortality, length of ICU stay and length of hospital stay. Results: During the study period, a total of 87 patients were admitted in the medical ICU. In 29 patients, criteria of sepsis or outcome of ICU stay were not met, and were excluded from the study. Out of the 48 patients included in the study, 35 patients died and 13 patients survived to transfer out from ICU. Age and sex were similar between them. Data was analyzed for associations. In univariate analysis, there was no association between the platelet counts and disease severity scores, except for Plat-nadir exhibiting a weak negative association with SOFA score at admission (Pearsons R: - 0.303, p= 0.036). Mortality was associated with platelet fall, APACHE-II and SOFA scores at admission (Table 2). A unit increase in APACHE-II-adm and SOFA-adm, and an increment of 10,000 in Plat-fall, increased the odds ratio (OR) of mortality by 14%, 33% and 21% respectively. Multivariate analysis was carried using logistic regression methodology and none of the aforesaid were associated with mortality. It is notable that platelet fall narrowly missed independent association, p= 0.07. Conclusion: This study demonstrates that patients with larger fall in platelet counts may be at increased risk of dying. Larger, prospective studies are needed to further clarify the association of platelet count with outcome of ICU stay.