The LODS (Logistic Organ Dysfunction Score) was developed by Le Gall et al. in 1996. The developmental database for this score was assembled as part of the European/North American Study of Severity Systems (ENAS) that was used to develop the Simplified Acute Physiology Score (SAPS II) system for estimating the probability of mortality among ICU patients. Data on 14745 consecutive ICU admissions were collected in 137 medical, surgical, or mixed ICUs in 12 countries to develop and validate the LODS. 80% of the patients in the database were randomly selected to constitute the developmental sample, and the remaining 20% composed the validation sample. As with the development of SAPS II, differences by site were not a consideration in the development of the system.
Although the LODS is calculated on the basis of a logistic equiation with the statistical technique of multiple logistic regression we must take into account that the score not a genuine logistic score since it has been transformed into an additive model later in the developmental process. Its points are allocated for the neurologic, cardiovascular, and renal dysfunction as well as the pulmonary, hematologic, and hepatic systems and addresse both the relative severity among organ systems and the degree of severity within an organ system. The total number of points provides an estimated risk of mortality. The additive score correlates with the rate of mortality in percent.