Evaluating maternity care using national administrative health datasets: How are statistics affected by the quality of data on method of delivery?

Table 2 Impact of mode of delivery definition on resulting maternity statistics: three case studies

Definition rule	Numerator	Denominator	# Trusts	Rate (%)
Emergency caesarean section rate
1	89,572	624,199	151	14.35
2	75,370	550,763	140	13.68
3	70,298	525,192	140	13.39
4	81,964	573,497	140	14.29
5	82,701	578,223	140	14.30
Third and fourth degree perineal tear rate amongst instrumental deliveries
1	5,049	76,161	144	6.63
2	4,260	64,661	136	6.59
3	3,965	60,281	135	6.58
4	4,640	70,268	133	6.60
5	4,686	71,205	133	5.58
Elective caesarean section rate for breech presentation
1	11,852	23,640	147	50.14
2	10,066	21,691	139	46.41
3	9,378	17,834	138	52.58
4	10,919	21,776	136	50.14
5	10,928	21,851	136	50.01

Key to definition rules.
1 = Use all episodes with an OPCS method of delivery code & base method of delivery definitions on OPCS codes alone.
2 = Use all episodes with a delmeth code & base method of delivery definitions on delmeth codes alone.
3 = Use only episodes in which both OPCS and delmeth codes are present and in agreement; base method of delivery definitions on agreed method of delivery code.
4 = Use all episodes with an OPCS method of delivery code excluding those from trusts with a poor agreement rate; base method of delivery definitions on OPCS codes alone.
5 = Use all episodes excluding those from trusts with a poor agreement rate; base method of delivery definitions on OPCS codes, or delmeth codes if OPCS codes are missing.

ISSN: 1472-6963