Eighty-three patients were included, of which 43 were women (52%) and 40 men (48%) with a mean age of 47 years (range from 19 to 87). There was no difference regarding the distribution of patients with regard to age or gender in both groups. The causes of sepsis were "mixed" (50.6%), pneumonia (14.4%), abdominal (14.4%), and others.
In our cohort, 18 patients died, with an overall mortality of 21.6%. The primary diagnoses of these patients were pneumonia (50%), followed by sepsis of abdominal origin (38.9%), with a relevant statistical difference (p = 0.002).
The APACHE-II and SOFA clinical scores were evaluated in all patients. In the surviving patients, both scores were lower than those who died. It was observed that non-surviving patients had higher lactate levels on admission to the emergency room. This finding also occurred with the L/P ratio, with a mean of 81.79 in non-surviving patients, compared to 21.93 in patients alive by day 30 (Table 1).
Table 1
Comparison of patient variables between survivors and non-survivors.
| Survivors | Non-survivors | p-value |
Age, years | 48.4 ± 18.99 | 45.4 ± 12.95 | 0.533 |
Clinical SCORES |
SOFA score | 7.2 ± 4.53 | 12.27 ± 5.61 | < 0.001 |
APACHE-II score | 12.02 ± 6.19 | 16.1 ± 6.32 | 0.018 |
Lactate mg/dL | 2.13 ± 2.05 | 4.98 ± 3.33 | < 0.001 |
Pyruvate mmol/L | 150.7 ± 82.47 | 105.07 ± 86.35 | 0.028 |
L/P ratio | 21.93 ± 31.9 | 81.79 ± 73.01 | 0.003 |
Sepsis origin, n (%) |
Pneumonia | 3 (6.0) | 9 (50.0) | 0.002 |
Abdominal | 5 (10) | 7 (38.9) | |
Others | 42 (84) | 2 (11.1) | |
Other variables, n (%) |
Shock on admission | 13 (26.0) | 14 (77.8) | < 0.001 |
Hemodialysis | 17 (34) | 8 (44.4) | 0.570 |
Cirrhosis | 10 (20.0) | 7 (38.9) | 0.126 |
Cancer | 11 (22) | 8 (44.4) | 0.123 |
L/P, lactate/pyruvate ratio; APACHE II, Acute Physiology and Chronic Health Evaluation; SOFA, Sequential Organ Failure Assessment. |
It is important to note that aside from the higher mean initial serum lactate of non-surviving patients, marked hypopyruvatemia was found with a mean of 105.07 ummol/L, which is associated with the disproportionately high L/P ratio in this group. In comparison, normal levels of pyruvate between 120–150 mmol/L were found in the literature.
Also, patients with hemodynamic variables compatible with septic shock on admission to the emergency room had higher mortality, conferring statistical relevance to the univariate analysis (Table 1).
Although serum lactate and pyruvate showed independently different means in both groups, it is evident that when determining the L/P ratio, the statistical difference becomes more pronounced if it is monitored every 4 hours after arrival at the emergency room.
Notably, all patients who developed an L/P ratio > 25 over 4 hours or more died. Likewise, it should be noted that two patients from the group of non-survivors had an L/P ratio < 25 on admission, which increased to > 25 after 4 hours. (Fig. 1)
It is also interesting that when contrasting mortality through survival curves (log-rank), an improvement of at least 30% in the L/P ratio in the next 4 hours on arrival to the emergency room confers a statistically significant protective effect in the short-term in patients with severe sepsis. (Fig. 2)
Last, we performed a binary logistic regression to determine the variables with the greatest impact on mortality. It was found that the most important variable is the L/P ratio > 25 with an OR of 4.73, conferring higher mortality in these patients. Likewise, a reduction of at least 30% in the L/P ratio in our study conferred a protective effect, with an OR of 0.78. The SOFA and APACHE-II scores did not show statistical differences. (Table 2.)
Table 2
Clinical variables with greater relevance regarding mortality.
Variables | OR ( 95% CI) | p-value |
Initial L/P ratio > 25 | 4.73 ( 1.63–7.83 ) | < 0.001 |
Reduction of L/P ratio > 30% | 0.78 ( 0.61–0.95 ) | 0.047 |
APACHE II > 10 | 3.1 ( 0.8–5.4 ) | 0.073 |
SOFA ≥ 6 | 3.92 ( 0.42–7.42 ) | 0.097 |
OR, odds ratio; L/P, lactate/pyruvate ratio; APACHE II, Acute Physiology and Chronic Health Evaluation; SOFA, Sequential Organ Failure Assessment. |