TABLE 2.

Validation of non-live birth outcome algorithms

Analysis	No. of cases reviewed	% retained	No. of true cases	% retained	PPV (95% CI), %
Stillbirth
Primary definition: ≥ 1 inpatient codes	100		71		71.0 (61.1–79.6)
Exclude cases with codes for other pregnancy outcomes within ±5 days	72	72.0%	58	81.7%	80.6 (69.5–88.9)
Spontaneous abortion
Primary definition: ≥ 1 inpatient or ≥2 outpatient codes	100		79		79.0 (69.7–86.5)
Exclude cases with codes for other pregnancy outcomes within ±5 days	59	59.0%	51	64.6%	86.4 (75.0–94.0)
Secondary definition: ≥ 1 inpatient or outpatient codes	250		193		77.2 (71.5–82.3)
Exclude cases with codes for other pregnancy outcomes within ±5 days	171	68.4%	148	76.7%	86.6 (80.5–91.3)
Termination
Primary definition: ≥ 1 inpatient or ≥2 outpatient codes	100		93		93.0 (86.1–97.1)
Exclude cases with codes for other pregnancy outcomes within ±5 days	85	85.0%	83	89.2%	97.7 (91.8–99.7)
Secondary definition: ≥ 1 inpatient or outpatient codes	277		234		84.5 (79.7–88.5)
Exclude cases with codes for other pregnancy outcomes within ±5 days	217	78.3%	206	88.0%	94.9 (91.1–97.4)
Composite non-live birth outcomes
Primary definition	297a		274		92.3 (88.6–95.0)
Secondary definition	623b		588		94.4 (92.3–96.1)

^aOut of 300 potential non-live birth cases, 3 duplicates were removed as they were selected for more than one non-live birth sample for validation. This duplication occurred because each non-livebirth cohort was created independently, and codes indicative of different non-live birth outcomes could have been recorded close in time. For the composite non-live birth outcome, a case was considered to be a true positive as long as the non-live birth outcome was confirmed, regardless of the specific type of non-live birth.

^bOut of 627 potential non-live birth cases, 4 duplicates were removed as they were selected for more than one non-live birth sample for validation.