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. 2023 Mar 31;23(1):103.
doi: 10.1186/s12871-023-02015-1.

Non-thyroidal Illness Syndrome (NTIS) is no independent predictor for mortality in ICU patients

Natalie Krug  1 , Sven Bercker  1 , Thilo Busch  1 , Steffen Friese  1 , Nora Jahn  1   2 , Maria Theresa Voelker  3
Affiliations

Non-thyroidal Illness Syndrome (NTIS) is no independent predictor for mortality in ICU patients

Natalie Krug et al. BMC Anesthesiol. .

Abstract

Background: Low T3-(/T4-) syndrome, also known as non-thyroidal Illness Syndrome (NTIS) describes a decrease in free serum thyroid hormones without a concomitant increase in TSH, frequently observed in critically ill patients. However, whether NTIS is only a metabolic adaption to stress in critically ill or plays a crucial role as an independent risk factor for ICU mortality, remains unknown. Our study aimed to evaluate NTIS as an independent risk factor for increased ICU mortality.

Methods: All patients admitted to the interdisciplinary intensive care unit (ICU) at the University Hospital of Leipzig between 2008 and 2014 were retrospectively analyzed for thyroidal function. Baseline data, information on additional thyroid function tests, disease progression, hospital and ICU length of stay (LOS) and patient outcome were retrospectively analyzed from the hospitals digital information system. For statistical evaluation, univariate analysis, matched pairs analysis and multivariate logistic regression were conducted.

Results: One thousand, seven hundred ninety patients were enrolled in the study, of which 665 showed NTIS. Univariate analysis revealed a positive association of NTIS with ICU- and hospital-LOS, need for mechanical ventilation, incidence of sepsis, acute respiratory distress syndrome, acute liver failure and increased ICU mortality. Results of matched pair analysis confirmed these findings. In multivariate logistic regression, NTIS was associated with an increased ICU-LOS, increased duration of mechanical ventilation, acute kidney injury and liver failure, but showed no independent association with increased ICU-mortality.

Conclusion: Duration of mechanical ventilation as well as incidence of acute kidney injury, sepsis and acute liver failure were detected as independent predictors of mortality in patients with NTIS. NTIS itself was no independent predictor of increased ICU-mortality.

Keywords: Critical illness; Intensive care; Thyroid axis; Thyroid hormones.

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Conflict of interest statement

All authors declare to have no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Figures

Fig. 1
Fig. 1
Enrolment of patients
Fig. 2
Fig. 2
Independent risk factor for NTIS Low fT3 and NTIS Low fT3 fT4. Multivariate logistic regression of risk factors for NTIS Low fT3 fT4 (A) and NTIS Low fT3 (B); forest plot; full data may be found in the supplements section (Suppl. Tables 1 and 2); ICU: intensive care unit; LOS: length of stay; ARDS: Acute Respiratory Distress Syndrome
Fig. 3
Fig. 3
Hospital mortality NTIS Low fT3. Multivariate logistic regression of risk factors for hospital mortality of patients with NTIS Low fT3; Forest blot; binary logistic regression including n = 381 patients with NTIS Low fT3. SAPS: Simplified Acute Physiology Score; mech.: mechanical; ARDS: Acute Respiratory Distress Syndrome; AKI: acute kidney injury; ICD-10: International Classification of Diseases
Fig. 4
Fig. 4
Hospital mortality NTIS Low fT3 fT4. Multivariate logistic regression of risk factors for hospital mortality of patients with NTIS Low fT3; Forest blot; odds ratio for liver failure 29.6 (lower value 8.3; upper value 104.0) binary logistic regression including n = 284 patients with NTIS Low fT3. SAPS: Simplified Acute Physiology Score; mech.: mechanical; ARDS: Acute Respiratory Distress Syndrome; AKI: acute kidney injury; ICD-10: International Classification of Diseases
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