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17. All-Cause 30-Day Hospital Readmission Rate

HardBusiness AnalyticsPostgreSQL 16PRO
Table: inpatient_discharges
+----------------+------+
| Column Name    | Type |
+----------------+------+
| discharge_id   | int  |
| patient_id     | int  |
| discharge_date | date |
+----------------+------+

discharge_id is the unique key for this table. Each row contains record details for this enterprise dataset.

Table: next_admissions
+----------------+------+
| Column Name    | Type |
+----------------+------+
| admission_id   | int  |
| patient_id     | int  |
| admission_date | date |
+----------------+------+

admission_id is the unique key for this table. Each row contains record details for this enterprise dataset.

Hospital clinical quality committees track patient readmissions occurring within 30 days of prior inpatient discharge to assess post-acute care coordination.

Write a query to calculate readmissions occurring between 1 and 30 days after initial inpatient discharge. 1. In a CTE `readmission_cases`, find hospital admissions (`a2`) for the same patient where `a2.admission_date > a1.discharge_date AND a2.admission_date <= a1.discharge_date + 30`. 2. In the outer query, calculate total index discharges and count of patients readmitted. Return: 1. `total_index_discharges`: Count of all records in `inpatient_discharges` 2. `readmitted_count`: Count of unique patients with a 30-day readmission 3. `readmission_rate_pct`: `ROUND(readmitted_count * 100.0 / total_index_discharges, 1)` (No ORDER BY needed for single-row summary).

Return the result table ordered as specified. The result format is in the following example.

Example 1:
Input:
Preparing sample rows...
Output:
Calculating benchmark target...
Explanation:

Inpatient 30-day readmission metric summary.

Constraints:
  • Query must utilize clause(s): WITHJOINROUND
  • Result order matters (tie-breakers and sort order must be strictly preserved).
  • Engine: PostgreSQL 16 standard syntax (in-browser WASM).
query.sql|PostgreSQL 16 WASM
Loading SQL editor...
You must run your code first

Write your SQL query in the editor and click Run or Submit to test against in-browser PostgreSQL 16 WASM.

About the “All-Cause 30-Day Hospital Readmission Rate” SQL Problem

Business Scenario

Hospital clinical quality committees track patient readmissions occurring within 30 days of prior inpatient discharge to assess post-acute care coordination.

Expected Output & Criteria

Inpatient 30-day readmission metric summary.

Database Table Schema (PostgreSQL DDL)

PostgreSQL 16 WASM
CREATE TABLE inpatient_discharges (
        discharge_id INT PRIMARY KEY,
        patient_id INT NOT NULL,
        discharge_date DATE NOT NULL
      );

      CREATE TABLE next_admissions (
        admission_id INT PRIMARY KEY,
        patient_id INT NOT NULL,
        admission_date DATE NOT NULL
      );

Target SQL Clauses & Operators

WITHJOINROUND

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