# SAPS-II and Sepsis-3 on vanilla PostgreSQL MIMIC-III v1.3

This folder contains the SQL scripts needed to compute, on a stock
PostgreSQL restore of the MIMIC-III v1.3 dump:

- the **Simplified Acute Physiology Score II (SAPS-II)** — a
  one-row-per-ICU-stay severity score computed on day 1; and
- the **Sepsis-3 onset time** (Singer et al., JAMA 2016) — the
  earliest hour at which a patient has SOFA ≥ 2 within ±48 h
  of suspicion of infection.

The SAPS-II scripts are mirrored verbatim from the upstream repository
[`MIT-LCP/mimic-code`](https://github.com/MIT-LCP/mimic-code) (specifically
the `mimic-iii/concepts_postgres/` tree, the auto-generated PostgreSQL
port of the BigQuery concepts).  The Sepsis-3 pipeline is bespoke:
upstream ships only an empty stub for MIMIC-III, so we adapted the
MIMIC-IV scripts under `mimic-iv/concepts/{score,sepsis,medication}/`
to MIMIC-III's schema (see "Sepsis-3 port notes" below).

## Files

```
sql/
├── build_sapsii.sql                       <-- master runner for SAPS-II
├── build_sepsis3.sql                      <-- master runner for Sepsis-3
├── postgres-functions.sql                 <-- PL/pgSQL shims for DATETIME_DIFF / _ADD / _SUB
├── echo_data.sql                          <-- weight imputation helper
├── durations/
│   ├── ventilation_classification.sql
│   ├── ventilation_durations.sql
│   ├── weight_durations.sql
│   ├── dobutamine_dose.sql
│   ├── dopamine_dose.sql
│   ├── epinephrine_dose.sql
│   └── norepinephrine_dose.sql
├── firstday/
│   ├── blood_gas_first_day.sql
│   ├── blood_gas_first_day_arterial.sql
│   ├── gcs_first_day.sql
│   ├── labs_first_day.sql
│   ├── urine_output_first_day.sql
│   └── vitals_first_day.sql
├── fluid_balance/
│   └── urine_output.sql                   <-- all-time UO; used by Sepsis-3
├── severityscores/
│   └── sapsii.sql
└── sepsis/                                <-- bespoke Sepsis-3 pipeline
    ├── blood_gas_arterial.sql             <-- all-time arterial BG (PaO2/FiO2)
    ├── gcs_all.sql                        <-- all-time GCS
    ├── sofa_hourly.sql                    <-- staged hourly SOFA pipeline
    ├── antibiotic.sql                     <-- filtered antibiotic prescriptions
    ├── suspicion_of_infection.sql         <-- abx <-> culture pairing
    └── sepsis3.sql                        <-- final onset table
```

## Dependency graph (SAPS-II)

```
postgres-functions.sql                 (DATETIME_* shims, used everywhere below)
│
├── durations/ventilation_classification.sql
│       └── durations/ventilation_durations.sql
│
├── firstday/blood_gas_first_day.sql
│       └── firstday/blood_gas_first_day_arterial.sql
│
├── firstday/gcs_first_day.sql
├── firstday/labs_first_day.sql
├── firstday/urine_output_first_day.sql
└── firstday/vitals_first_day.sql
        │
        └── severityscores/sapsii.sql      <-- final table: `sapsii`
```

## Dependency graph (Sepsis-3)

```
postgres-functions.sql
│
├── echo_data.sql
│       └── durations/weight_durations.sql
│               ├── durations/dobutamine_dose.sql
│               ├── durations/dopamine_dose.sql
│               ├── durations/epinephrine_dose.sql
│               └── durations/norepinephrine_dose.sql
│
├── fluid_balance/urine_output.sql        (all-time UO; consumed by sofa_hourly)
├── durations/ventilation_classification.sql
│       └── durations/ventilation_durations.sql
│
├── sepsis/blood_gas_arterial.sql         (all-time arterial PaO2/FiO2)
├── sepsis/gcs_all.sql                    (all-time GCS)
│       │
│       └── sepsis/sofa_hourly.sql        <-- table: `sofa_hourly`
│                                            (one row per ICU hour)
│
├── sepsis/antibiotic.sql
│       └── sepsis/suspicion_of_infection.sql
│
└── sepsis/sepsis3.sql                    <-- final table: `sepsis3`
                                              (one row per ICU stay)
```

`fluid_balance/urine_output.sql` is included because it appears in the
upstream `postgres-make-concepts.sql` and is harmless to build for
SAPS-II; for Sepsis-3 it is required (the renal-SOFA branch reads it).

## Required base MIMIC-III tables

The scripts assume the standard MIMIC-III v1.3 schema with these tables
already present and accessible via `search_path`:

`admissions`, `chartevents`, `diagnoses_icd`, `icustays`,
`inputevents_cv`, `inputevents_mv`, `labevents`, `microbiologyevents`,
`noteevents` (for `echo_data`), `outputevents`, `patients`,
`prescriptions`, `procedureevents_mv`, `services`.

## Running SAPS-II

1. Restore the MIMIC-III v1.3 dump into a PostgreSQL database (the usual
   `postgres_create_tables.sql` / `postgres_load_data.sql` flow from the
   `mimic-iii/buildmimic/postgres/` directory of the upstream repo).
2. Make sure the schema containing those tables is on your `search_path`
   (commonly `mimiciii`).
3. Run the master script from this directory:

   ```bash
   psql -d mimic -v ON_ERROR_STOP=1 \
        -c 'SET search_path TO mimiciii, public;' \
        -f sql/build_sapsii.sql
   ```

4. Query the result:

   ```sql
   SELECT subject_id, hadm_id, icustay_id, sapsii, sapsii_prob
   FROM   sapsii
   ORDER  BY icustay_id
   LIMIT  10;
   ```

## Running Sepsis-3

1. Same prerequisites as SAPS-II.
2. Run:

   ```bash
   psql -d mimic -v ON_ERROR_STOP=1 \
        -c 'SET search_path TO mimiciii, public;' \
        -f sql/build_sepsis3.sql
   ```

   Expect a few hours runtime on stock PostgreSQL with default
   indexes.  Most of that is the per-measurement scans of
   `chartevents` (~330 M rows), `labevents` (~30 M rows), and
   `outputevents` (~4 M rows) that drive the hourly SOFA pipeline.

3. Query the result:

   ```sql
   SELECT icustay_id, suspected_infection_time,
          sofa_time, sofa_score, sepsis3
   FROM   sepsis3
   WHERE  sepsis3 = TRUE
   ORDER  BY icustay_id
   LIMIT  10;
   ```

   For per-hour SOFA across the whole stay (e.g. for time-series
   modelling), query `sofa_hourly` directly.

### Sepsis-3 port notes

The Sepsis-3 onset definition is *time-stamped*: it requires a SOFA
score at any moment during the ICU stay, not just on day 1, because
suspicion of infection can fall anywhere in the stay.  MIMIC-IV
provides a hourly SOFA via a stack of pre-built `mimic_derived.*`
tables (`icustay_hourly`, `bg`, `vitalsign`, `gcs`,
`urine_output_rate`, `chemistry`, `enzyme`, `complete_blood_count`,
`epinephrine`, `norepinephrine`, `dopamine`, `dobutamine`,
`ventilation` with `ventilation_status='InvasiveVent'`).  Almost none
of those exist in `mimic-iii/concepts_postgres/`, so we ported the
needed bits inline.  Notable differences from MIMIC-IV behaviour:

1. **Hourly grid** is built inline with `generate_series` on
   `icustays.intime` / `outtime` (no `icustay_hourly` table).
2. **Ventilation status granularity** is missing.  MIMIC-IV's
   `InvasiveVent` filter (used to split `pao2fio2ratio_vent` from
   `pao2fio2ratio_novent` so a ventilated patient doesn't get a
   stratospheric SOFA respiratory score from a noisy unventilated
   PaO2:FiO2) doesn't have a clean MIMIC-III equivalent.  We use the
   lumped `ventilation_durations`, treating any active ventilation
   row as invasive ventilation.
3. **Urine output adjustment** is replicated inline in `sofa_uo`.
   We materialise both `uo_24hr` (sum) and `uo_tm_24hr` (count of
   distinct hours within the rolling 24 h window that actually had
   a UO observation), and the renal CASE in `sofa_components` uses
   `GREATEST(uo_24hr, 0) * 24.0 / uo_tm_24hr` only when
   `uo_tm_24hr BETWEEN 22 AND 30`, falling back to creatinine alone
   otherwise.  The `GREATEST(_, 0)` clip prevents patients on
   continuous bladder irrigation (which `fluid_balance/urine_output.sql`
   subtracts as a negative volume) from being mis-scored as
   oliguric.  Effect: at hours where the stay has lasted less than
   ~22 h or where charting is sparse, renal SOFA is computed from
   creatinine only, instead of being over-scored from a partial UO
   sum.
4. **Vasopressor rates** come from upstream
   `durations/{epinephrine,norepinephrine,dopamine,dobutamine}_dose.sql`,
   which already merge CareVue + MetaVision and convert to
   mcg/kg/min.  Weight-based unit conversion uses
   `weight_durations.sql`, which itself depends on `echo_data.sql`
   for weight imputation.
5. **Antibiotic time precision is one day.**  MIMIC-III
   `prescriptions.startdate` is DATE-precision only, so
   `antibiotic_time` (and any sepsis-3 onset time driven by it)
   lands on midnight of the prescription start date.  Suspicion of
   infection driven by a culture with charttime is still
   timestamped to the minute.

The hourly SOFA pipeline is built **column-by-column into staged
tables** (`sofa_grid`, `sofa_vs`, `sofa_gcs`, `sofa_bili`, `sofa_cr`,
`sofa_plt`, `sofa_pf`, `sofa_uo`, `sofa_vaso`, then `sofa_wide`,
`sofa_components`, `sofa_hourly`).  Each stage scans exactly one
giant raw table, so each stage can be `EXPLAIN ANALYZE`d
independently and re-run in isolation if you crash partway through.
The intermediates are kept (not dropped) so you can inspect them.

## Re-fetching from upstream

Re-run `fetch.ps1` (PowerShell, Windows) to pull the latest versions of
all upstream-mirrored scripts from the `main` branch of
`MIT-LCP/mimic-code`.  Files under `sql/sepsis/` are bespoke and not
fetched.

## Caveats

- Severity scores (SAPS-II, SOFA) and sepsis-3 are computed for
  **every** ICU stay, including neonates, re-admissions, and short
  stays.  Filter `icustay_id` yourself to match your study population
  (the canonical adult-ICU sepsis-3 cohort excludes patients < 18
  and ICU re-admissions, but we do not enforce that here).
- The PostgreSQL scripts in `concepts_postgres/` are auto-generated from
  the BigQuery-flavored originals in `concepts/`; the `DATETIME_*`
  function calls you'll see in the SQL are resolved by the wrappers in
  `postgres-functions.sql`, so it must be sourced first (the master
  scripts do this for you).