Effects Of Immune Function On Prognositic Outcome In Critical Ill Patients With Acinetobacter Baumannii Infection

Objective:To evaluate the effects of immune function on prognositic outcome in critical ill patients with Acinetobacter baumannii infection.Methods:This was a single-center, observational study. From July 2015 to March 2016, patients with Acinetobacter baumannii infection in the intensive care unit of Zhongda Hospital were enrolled. The enrolled day was defined as the D1. Age, ICU admission diagnosis, underlying diseases, APACHE ? score and infection site, were recorded. Body temperature, heart rate, white blood cell counts, procalcitonin, C-reactive protein, SOFA score and the level of CD4+, CD8+, Th1, Th2 and HLA-DR in the blood measured by flow cytometry on the D1, D3 and D7 were recorded. During a 28-day period, days of vasoactive drugs usage, mechanical ventilation, CRRT, and the lengths of ICU and hospital stay were recorded. Patients were divided into the survival group and the non-survival group according to 28-day survival.Results:Seventy-nine patients with Acinetobacter baumannii infection were screened,39 patients were excluded, and 40 patients were enrolled finally. Twenty-three (57.5%) patients survived in the 28 day period. The 28 day mortality was 42.5%.1. Patients' characteristics:There were no significant differences in term of age, gender, infection sites, underlying diseases and APACHE ? scores between the two groups.2. Systemic inflammatory response:No significant differences of temperature, heart rate, white blood cell counts, levels of procalcitonin and C-reactive protein were observed between the two groups.3. Changes of immune function(1)Th1/Th2 ratio:Early immunosuppressive were observed in both group at D1 showed as Th1/Th2 ratio> 0.22. In survival group, Th1/Th2 ratio reached peak value at D3[0.58(0.45-0.97),P=0.231] and significantly decreased at D7[0.47(0.32-0.62), P<0.05]. However, in non-survival group, Th1/Th2 ratio increased continuously, which were significantly higher on D7 [1.19(1.00-1.37)] when compared with that at Dl [0.55(0.42-0.75), P<0.05] and D3[0.86(0.70-1.19), P<0.05]. Comparison with survival group, Th2/Thl ratio were significantly higher in non-survival group at D3 and D7 [0.86(0.70-1.19), 1.19(1.00-1.37), P<0.05].(2)mHLA-DR:In survival group, mHLA-DR reached lowest value at D3[80.4(63.3-86.3),P<0.05] and significantly increased at D7 [93.3(84.4-98.4), P<0.05]. However, in non-survival group, mHLA-DR decreased continuously, which were significantly lower at D7 [58.3(36.9-71.5)] when compared with that at D1 [81.9(73.4-87.9), P<0.05]and D3[65.3(61.8-76.4), P<0.05]. Comparison with survival group, mHLA-DR were significantly lower in non-survival group at D7 [93.3(84.4-98.4) vs.58.3(36.9-71.5), P<0.05].(3) CD4+/CD8+ ratio:In the survival group, the level of CD4+/CD8+ reached lowest value at D3, but there were no statistical difference among Day 1, Day 3 and Day 7(P> 0.05). In the non-survival group, CD4+/CD8+showed a consistently decreased trend, but there were no statistical difference among different time point (P> 0.05). At each time point, there were no significant differences of CD4+/CD8+ ratio between groups.(4) Lymphocytes:In the survival group, the level of lymphocytes reached lowest value at D3, but there were no statistical difference among Dl, D3 and D7(P> 0.05). Lymphocytes showed a consistently decreased trend in the non-survival group, but there were no statistical difference among different time point (P> 0.05). At each time point, there were no significant differences of lymphocytes between groups.(5) NLCR:In the survival group, the level of NLCR at D7 was significantly decreased than that at D1(P<0.05). The level of NLCR at D7 was significantly increased than that at D1 (P<0.05) in the non-survival group. Comparison with survival group, NLCR were significantly higher in non-survival group at D7 [16.2(13.2-22.9) vs.6.5(3.9-8.9), P<0.05].4. Organ dysfunctions between two groups:Comparison with survival group, SOFA scores were significantly higher in non-survival group at D1, D3 and D7 (P<0.05). Days of vasoactive drugs usage and CRRT in the non-survival group were significantly longer(P<0.05). No significant differences of the mechanical ventilation days and the length of ICU stay were observed between the two groups.5. Predictive value of:The Th2/Thl ratio at D7 had greater discriminatory ability than the other immune parameters to predict 28-day mortality in critically ill patients with Acinetobacter baumannii infection, with area under the curve (AUC) values was 0.969. The best prediction threshold was 0.89, the sensitivity was 100%, and the specificity was 91%; the positive predictive value was 0.92, and the negative predictive value was 0.81.Conclusion:Our results demonstrated that the immunosuppressive emerged in the early phase of patients with Acinetobacter baumannii infection. Persistently immunosuppressive was associated with poor outcome. Th2/Th1 ratio provide reliable predictor of poor outcome.