The SAIL databank: linking multiple health and social care datasets

Table 2 Levels of matched records using a variety of techniques.

	Levels of matched records
	Primary Care General Practice (GP dataset)		Secondary Care Hospital Admissions (PEDW dataset)		Social Services (PARIS database)
	Number	%	Number	%	Number	%
Sample size	229,127		290,650		18,540
Valid NHS Number	229,117	99.996%	264,868	91.13%	-	0.00%
Valid NHS Number plus DRL:	229,123	99.998%	280,729	96.59%	14,158	76.36%
Valid NHS Number plus PRL (99% cut off):	229,125	99.999%	287,572	98.94%	17,095	92.21%
Valid NHS Number plus PRL (95% cut off):	229,125	99.999%	288,186	99.15%	17,431	94.02%
Valid NHS Number plus PRL (90% cut off):	229,125	99.999%	288,424	99.23%	17,553	94.68%
Valid NHS Number plus PRL (50% cut off):	229,125	99.999%	288,670	99.32%	17,639	95.14%
Overall combining Valid NHS, DRL & PRL (50%):	229,125	99.999%	288,683	99.32%	17,642	95.16%

The numbers (and percentages) of records that could be matched using deterministic record linkage (DRL) and a various thresholds of probabilistic record linkage (PRL) were assessed for each of three test datasets: the GP dataset, the PEDW dataset and the PARIS database. Records with a valid NHS number were accepted. The matching rate achieved by applying DRL followed by PRL (to the 50% threshold) was also assessed, and the final row shows this result of operating the MACRAL algorithm as illustrated in Figure 1.

ISSN: 1472-6947