Sepsis is systemic inflammation caused by an infection, which results in fever, increased heart rate, and confusion. It is an important health concern, striking more than one million Americans each year. Around 30 – 50% of people die from the condition.
Researchers are interested in studying the relationship between sepsis and vitamin D because the current treatment options for the condition are often inadequate and have undesirable side effects. Moreover, vitamin D has been found to beneficially modulate inflammation and increase resistance to infections.
However, whether vitamin D deficiency affects the prognosis of sepsis is still controversial. Some studies find no association between vitamin D status and mortality in sepsis patients.
In a new study out of China, researchers selected 236 septic patients admitted to a medical or surgical intensive care unit to determine if vitamin D status influenced prognosis of sepsis.
They collected data at baseline on vitamin D status, parathyroid hormone (PTH) status, Acute Physiology and Chronic Health Evalutation (APACHE) II score, and Sequential Organ Failure Assessment (SOFA) score.
APACHE is a severity-of-disease classification system applied within 24 hours of admission of a patient to an intensive care unit, and uses a score from 0 to 71 based on several different measurements. Higher scores indicate a more severe disease condition and a higher risk of death.
SOFA is a scoring system used to determine the extent of a patient’s organ function or rate of failure. Higher scores correspond to increased rate of organ failure and increased mortality rates.
Patients were classified as PTH responders if they had PTH levels greater than 75 pg/ml and non-responders if they had levels of 75 pg/ml or less. Since PTH stimulates the activation of vitamin D, elevated PTH levels indicate a greater biological need for activated vitamin D.
The researchers were trying to determine if vitamin D status was related to 28-day mortality in these septic patients, and whether this relationship varied according to PTH levels.
Analyses of the data revealed:
- Of the 236 patients, 75, 100, and 61 were diagnosed with vitamin D deficiency, insufficiency, and sufficiency, respectively.
- Patients with vitamin D deficiency had significantly higher APACHE scores (p< 0.001), SOFA scores (p<0.001), PTH levels (p<0.001), and 28-day mortality (p<0.001) compared to vitamin D insufficient and sufficient patients.
- The mean survival time of patients with vitamin D deficiency was 18.4 days and the survival time of patients with vitamin D insufficiency or sufficiency was 24.3 days.
- Within the vitamin D deficient patients, PTH responders had a higher 28-day mortality rate than did non-responders.
The high rate of vitamin D deficiency or insufficiency, 74.1%, is in line with previous studies in adult ICU patients.
The research team stated,
“In conclusion, hypovitaminosis D in septic patients is associated with higher PCT levels, and vitamin D deficiency is an independent risk factor for 28-day mortality. Additionally, hypovitaminosis D is associated with higher mortality when present in PTH responders than in non-responders.”
Because of the observational study design, a cause-and-effect relationship can’t be established from the results.
Another limitation of the study is that vitamin D and PTH levels were only measured at baseline and were not monitored throughout the duration of the study.
The finding that within vitamin D deficient patients, higher PTH levels were associated with increased mortality is expected.
Elevated PTH levels are related to increased mortality among older individuals in the general population and can lead to suppression of the immune system, making a patients more susceptible to infections.
The next step for research is intervention studies in which vitamin D deficiency is treated in septic patients in the ICU by supplementation and various clinical outcomes, including mortality, are measured.