The SOFA (Sequential Organ Failure Assessment) score is a commonly used
assessment tool for tracking a patient's status during a stay at an ICU.
Organ function is quantified by aggregating 6 individual scores,
representing respiratory, cardiovascular, hepatic, coagulation, renal and
neurological systems. The function sofa_score() is used as callback
function to the sofa concept but is exported as there are a few arguments
that can used to modify some aspects of the presented SOFA implementation.
Internally, sofa_score() calls first sofa_window(), followed by
sofa_compute() and arguments passed as ... will be forwarded to the
respective internally called function.
sofa_score(
...,
worst_val_fun = max_or_na,
explicit_wins = FALSE,
win_length = hours(24L),
keep_components = FALSE,
interval = NULL
)sofa_resp(..., interval = NULL)
sofa_coag(..., interval = NULL)
sofa_liver(..., interval = NULL)
sofa_cardio(..., interval = NULL)
sofa_cns(..., interval = NULL)
sofa_renal(..., interval = NULL)
A ts_tbl object.
Concept data, either passed as list or individual argument
functions used to calculate worst values over windows
The default FALSE iterates over all time steps,
TRUE uses only the last time step per patient and a vector of times will
iterate over these explicit time points
Time-frame to look back and apply the worst_val_fun
Logical flag indicating whether to return the
individual components alongside the aggregated score (with a suffix _comp
added to their names)
Time series interval (only used for checking consistency
of input data, NULL will use the interval of the first data object)
The function sofa_score() calculates, for each component, the worst value
over a moving window as specified by win_length, using the function
passed as worst_val_fun. The default functions max_or_na() return NA
instead of -Inf/Inf in the case where no measurement is available over an
entire window. When calculating the overall score by summing up components
per time-step, a NA value is treated as 0.
Building on separate concepts, measurements for each component are converted to a component score using the definition by Vincent et. al.:
| SOFA score | 1 | 2 | 3 | 4 |
| Respiration | ||||
| PaO2/FiO2 [mmHg] | < 400 | < 300 | < 200 | < 100 |
| and mechanical ventilation | yes | yes | ||
| Coagulation | ||||
| Platelets [×103/mm3] | < 150 | < 100 | < 50 | < 20 |
| Liver | ||||
| Bilirubin [mg/dl] | 1.2-1.9 | 2.0-5.9 | 6.0-11.9 | > 12.0 |
| Cardiovasculara | ||||
| MAP | < 70 mmHg | |||
| or dopamine | ≤5 | > 5 | > 15 | |
| or dobutamine | any dose | |||
| or epinephrine | ≤0.1 | > 0.1 | ||
| or norepinephrine | ≤0.1 | > 0.1 | ||
| Central nervous system | ||||
| Glasgow Coma Score | 13-14 | 10-12 | 6-9 | < 6 |
| Renal | ||||
| Creatinine [mg/dl] | 1.2-1.9 | 2.0-3.4 | 3.5-4.9 | > 5.0 |
| or urine output [ml/day] | < 500 | < 200 |
Adrenergica agents administered for at least 1h (doses given are in [μg/kg · min]
At default, for each patient, a score is calculated for every time step,
from the first available measurement to the last. In instead of a regularly
evaluated score, only certain time points are of interest, this can be
specified using the explicit_wins argument: passing for example
hours(24, 48) will yield for every patient a score at hours 24 and 48
relative to the origin of the current ID system (for example ICU stay).
Vincent, J.-L., Moreno, R., Takala, J. et al. The SOFA (Sepsis-related Organ Failure Assessment) score to describe organ dysfunction/failure. Intensive Care Med 22, 707–710 (1996). https://doi.org/10.1007/BF01709751