Low linkage rates between births and NPD

[bobbieupton]

Question / Problem statement

I'm trying to link birth records in HES to the NPD. For kids born prior to 2003 in our NPD dataset, we see much lower rates of linking to birth records (around a third of the NPD records with births before 2003 find a match in the HES APC datasets). We also see the majority of births in HES prior to 2003 not being matched to NPD records (compared to under 10% after 2003). Is this to be expected? We also don't have 2003 or 2011 APC which further restricts our sample of NPD records with matched birth records. Any guidance or help would be greatly appreciated!

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[zcabh35]

Howdy, this is expected. We suspect this is to do with the fact that in 2003 NHS numbers were introduced for babies

[klharron]

Hi,
As Vincent says, the introduction of NHS numbers for babies at the end of 2002 means that linkage between birth records and subsequent HES records became more more reliable after this time. So, this explains the lower linkage rates that you are seeing before this time.

When you say you don't have APC for 2003 or 2011, is this something that you've already flagged with the team or would you like us to look into this?

Katie

[bobbieupton]

Hi Katie, thanks for your reply - that's helpful. It would be great if you could look into the missing years of APC (2003 and 2011). I'm not sure if it's a feature of ECHILD or just erroneous. Any help would be great!

[klharron]

Can you email ich.echild@ucl.ac.uk please and we'll notify the ONS. Thanks.