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Table 2 NHS Digital match algorithm

From: Assessing the impact of specialist home visiting upon maltreatment in England: a feasibility study of data linkage from a public health trial to routine health and social care data

Step (match rate)a

NHS number

DoB

Sex

Postcode

1

Exact

Exact

Exact

Exact

2

Exact

Exact

Exact

–

3

Exact

Partial

Exact

Exact

4

Exact

Partial

Exact

–

5

Exact

–

–

Exact

6b

–

Exact

Exact

Exact

7c

–

Exact

Exact

Exact

8

Exact

–

–

–

  1. aMatching at step 1 or 2 would provide greatest reassurance of valid match
  2. bWhere NHS number does not contradict the match and DOB is not 1 January and the postcode is not in the ‘ignore’ list
  3. cWhere NHS number does not contradict the match and DOB is not 1 January
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