One physiologic score, one published mortality model. Choose the model by the data you collected, not by the output you want. PRISM IV covers the first 4 hours of PICU care, with laboratory values from 2 hours before admission through the first 4 hours (Pollack 2013), and gives the score and a mortality probability. PRISM III covers the first 12 or 24 hours and gives the score and its subscores only, with no probability. The 12- and 24-hour collections are one option here because the score arithmetic is identical for both. What the literature calls PRISM III-12 and PRISM III-24 are two mortality models this platform does not ship. A longer window catches more extreme values and so runs higher, so hold the collection period constant within any series and record which one was used. Seventeen variables are scored against age-banded thresholds and summed, 0 to 74, decomposing into a neurologic subscore (pupillary reflexes 0 to 11 plus mental status 0 to 5, maximum 16) and a non-neurologic subscore (the other fifteen variables, maximum 58). The age bands are neonate under 1 month, infant 1 to under 12 months, child 12 months to under 12 years, and adolescent 12 years and over. Enter the single most abnormal value reached inside the window for each variable. Several row shapes are easy to get wrong. Acidosis is one row satisfied by either the lowest pH or the lowest total CO₂, scored once at the worse tier, while the highest pH is a separate row, so a pH swinging from 6.9 to 7.6 scores on both. Total CO₂ likewise scores once at the low end and again at the high end. Prothrombin and partial thromboplastin time share a single row, scored once even when both qualify. Both pupils fixed, each larger than 3 mm, is the heaviest single item at 11 points. Enter the Glasgow Coma Scale only for known or suspected acute CNS disease, and never within 2 hours of sedation, paralysis or anaesthesia. Correct whole-blood chemistry before entry: glucose up by 10%, potassium by 0.4 mmol/L. Blank components score zero, so a partially entered score reads lower than the patient is. The PRISM IV probability is not computed from the total. It weights the neurologic subscore at 0.197 per point and the non-neurologic subscore at 0.163 per point, then adds age, admission source (operating room or post-anaesthesia care is the reference, and unplanned inpatient deterioration is the heaviest), CPR in the prior 24 hours, cancer, and low-risk system of primary dysfunction (endocrine, haematologic, musculoskeletal or renal, the model’s one protective term), and finishes with P = 1 / (1 + e^-R). That gives the estimated hospital mortality for a first PICU admission. The probability appears only when all four admission-context questions have been answered; a blank withholds it rather than assuming the reference patient.

PRISM is a case-mix and benchmarking instrument for groups of patients, not a bedside prognosis for the child in front of you. PRISM III shows no probability because Pollack 1996 prints the full score sheet and no regression coefficients, and the author note reserves the mortality equations for research use. The authors’ own network (CPCCRN) ships a score-only PRISM III calculator, which this implementation matches. PRISM IV’s coefficients, by contrast, were published with the stated objective of placing the algorithm in the public domain (Pollack 2016). Regional calibration. In the largest Saudi cohort (Riyadh, n = 4,019 admissions) PRISM III under-predicted death: SMR 2.61 overall, 3.96 in infants of 12 months and under, and 1.52 after excluding DNR patients, with AUC 0.81. Discrimination travels between populations; calibration frequently does not. Use the score for severity and case-mix description, and treat any PRISM mortality probability as uncalibrated for this region until it has been locally recalibrated. These evaluations cover PRISM III, not PRISM IV. Known source defects, handled explicitly. The patent’s neonate heart-rate band appears to carry an OCR error, printing 215-255 against a >225 cutoff; 215 to 225 is used here, following an independent reproduction. The glucose row prints 200 mg/dL and 11.0 mmol/L as if equivalent, and the mg/dL limb is authoritative: 200 mg/dL is 11.1 mmol/L. [NEEDS SOURCE]: no published worked example exists for either model, so the test fixtures were constructed from the threshold table, and round-trip reconciliation against the CPCCRN calculators is pending. The PRISM IV laboratory window starts 2 hours before PICU admission while its physiologic window starts at admission, so a referring-unit gas or chemistry from two hours out counts and a blood pressure from that same moment does not (Pollack 2013). The 12- and 24-hour collections are one option because PRISM III scores identically for both; the two separately calibrated PRISM III mortality models are not in the source article and are separately licensed. A longer collection usually yields a higher score, so a series should hold the period constant and record which was used. The PRISM IV probability is withheld while any of its four admission-context questions is blank, because a blank is not an answer of “no”, and those four questions are shown only under PRISM IV.

References

Pollack MM, Patel KM, Ruttimann UE. PRISM III: an updated Pediatric Risk of Mortality score. Crit Care Med. 1996;24(5):743-752.The derivation paper, and the source of the score. It publishes the score sheet in full (Figure 1) and NO regression coefficients: its eight tables were enumerated against the full text and Table 3, the one the Results section points to for the risk-factor models, compares model fit (chi-square, df, AIC, AUC, Hosmer-Lemeshow) rather than listing coefficients. There is no supplement. Its author note reserves the mortality equations for research use and states that non-research uses may attract compensation.PMID 8706448
Pollack MM, Holubkov R, Funai T, et al. The Pediatric Risk of Mortality Score: Update 2015. Pediatr Crit Care Med. 2016;17(1):2-9.PRISM IV. Source of the subscore split and every coefficient in Table 3. Its stated objective included placing the algorithms in the public domain.PMID 26492059 DOI 10.1097/PCC.0000000000000558
Pollack MM. Method, apparatus and medium for allocating beds in a pediatric intensive care unit and for evaluating quality of care. US patent 5,809,477. 1998.Primary source for the full PRISM III threshold table and the scoring notes quoted in the help text — the parts of the score the 1996 paper also publishes. Status: Expired - Lifetime, anticipated expiration 2015-09-21. It also states mortality equations the paper does not, but those are NOT implemented: the document is a single source for them, its transcription carries known internal inconsistencies, and it offers no page or table to cite.Source
Collaborative Pediatric Critical Care Research Network. PRISM IV calculator.The authors' own implementation, and the natural oracle for reconciling this one. Input and output sets read 2026-08-03: its input list matches Table 3 of Pollack 2016 one-to-one — same variables, same categories, same reference levels — and its reference age band tops out at 18 years. No case has been round-tripped through it, so the constructed fixtures here remain unreconciled against it.Source
Collaborative Pediatric Critical Care Research Network. PRISM III calculator.Retrieved 2026-08-03. Takes the 17 physiologic variables and an age band and returns SCORE, NEUROLOGIC and NON-NEUROLOGIC — no mortality, and it collects no risk factors with which to produce one. Pollack's own network had the coefficients and shipped the score without them, which is the practice this calculator now matches.Source
Alkhalifah AS, AlSoqati A, Zahraa J. Performance of pediatric risk of mortality III and pediatric index of mortality scores in a tertiary pediatric intensive care unit in Saudi Arabia. Front Pediatr. 2022;10:926686.King Fahad Medical City, Riyadh; n = 3396, children under 14. Its conclusion for the models it evaluated was 'sufficient discrimination ability and poor calibration', with the worst calibration AND discrimination in infants under 12 months. PRISM III discriminated best in the 60-120-month band (AUC 0.87). It evaluated PRISM III, not PRISM IV.DOI 10.3389/fped.2022.926686
Malhotra D, Nour N, El Halik M, Zidan M. Performance of Pediatric Index of Mortality 3 score in a tertiary pediatric ICU in Dubai. Dubai Med J. 2019;3(1):19–25.A PIM3 evaluation, not a PRISM one, and cited here for that reason explicitly. Latifa Hospital, Dubai; n = 583, 46 deaths (7.9%). Stable findings: AUC 0.78 (95% CI 0.69-0.87), overall SMR 0.53, and SMR 2.1 in sepsis. Its predicted-probability strata contradict each other and are carried as unstable: SMR 2.67 in the 1-5% band against SMR 0.33 below a predicted probability of 14.3% and 0.72 above it, so the same paper shows under-prediction and over-prediction in the same low range depending on where the bands are cut. It is the second Gulf data point for the pattern that does hold — discrimination survives the move between populations, calibration does not — which is why this page carries it alongside the Riyadh series rather than only naming its own model.DOI 10.1159/000505205
Pollack MM, Dean JM, Butler J, et al. The ideal time interval for critical care severity-of-illness assessment. Pediatr Crit Care Med. 2013;14(5):448-453.Source of the PRISM IV collection window this calculator states on the window field: physiologic variables from the first 4 hours of PICU care only, laboratory variables from 2 hours BEFORE admission through the first 4 hours. Added 2026-08-09, when that text was rewritten - the split was already being described on screen without naming where it came from. It is also the citation the authors' own CPCCRN calculators print beneath the same sentence.PMID 23628831
Alkhalifah AS, AlSoqati A, Zahraa J. Performance of Pediatric Risk of Mortality III and Pediatric Index of Mortality III Scores in Tertiary Pediatric Intensive Unit in Saudi Arabia. Front Pediatr. 2022;10:926686.FIRST-HAND — every figure below is taken from the paper itself (PMC9300935), not from a summary of it. 4,019 admissions across 2,620 patients at King Fahad Medical City, Riyadh, 2015-2019, drawn from the Virtual Pediatric Systems database. PRISM III SMR 2.61 (2.44-2.79) against PIM III 2.75; observed mortality 6.54% against 2.50% predicted; AUC-ROC 0.81 (0.79-0.84), rising to 0.87 (0.84-0.90) once DNR patients are excluded; SMR 3.96 (3.16-4.76) in infants 12 months and under; SMR 1.52 (1.24-1.80) excluding DNR. Authors' conclusion, quoted: 'Both models showed adequate discrimination ability, but poor calibration.'PMID 35874581 DOI 10.3389/fped.2022.926686

Reproduction rights

Freely reproducible.The PRISM III score — the variables, their age-banded ranges and every point value — is published in full in Pollack 1996 (Figure 1) and reproduced verbatim in US patent 5,809,477 (Pollack), which shows status 'Expired - Lifetime' with an anticipated expiration of 2015-09-21. PRISM IV's coefficients are printed in Table 3 of Pollack 2016 (PMID 26492059), whose stated objective included 'placing the algorithms (Pediatric Risk of Mortality IV) in the public domain', and the authors' own network publishes a free public calculator of it. PRISM III's MORTALITY equations are a separate matter and are NOT shipped: they appear in no table of the 1996 article, that paper's author note reserves them for research use and states that non-research uses may attract compensation, and their only source is the patent's transcription, which carries known internal inconsistencies and offers no page to cite. They are not shipped here in any form, and no PRISM III probability is emitted on any window.

Other mortality and severity scores

Paediatric Index of Mortality 3Predicted PICU mortality from data at first contact, for unit benchmarking

Important. For use by qualified health professionals as an informational and educational aid. It supports clinical judgment and does not replace it. Verify every result independently before making a clinical decision. This is not a medical device.