Single points of failure in people identification, HMRC and tax codes

One of our employees recently had one of those unwelcome notifications from HMRC informing him they had changed his tax code; they asserted that Bluewire were employing him as a second job, and therefore he had to pay £1500 in unpaid taxes.  HMRC thought he was also working for an agency we had never heard of. Now I guess he could be moonlighting, but given how hard he works for us, it’s rather unlikely.  Any spare time would more likely be spent playing TF2.

The HMRC had made a mistake, presumably a case of mistaken identity. Given that everyone has a unique National Insurance Number, this set me wondering how that error was made. Did someone do a search like ‘john smith bristol’ and then pick the name above or below the one they wanted? This is an established risk with pick lists and is something which should influence the way you design pick lists for drug prescribing. Not all suppliers do this which has led to some negative press reports. There is some good guidance on it here.

Perhaps the error had occurred as a consequence of using a single key field (e.g. National Insurance Number)  for identification which is an inherent risk of relying on a single key field. Incorporating a check digit as in the case of NHS Numbers partially mitigates against this, but only detects errors which alter the key field to an invalid one, not ones which alter it to another valid entry, which may reference a real entity.

Let’s consider administration of drugs at the bedside in hospitals. It is incumbent on the nurse to identify each patient correctly as step one. One strategy is to attempt to enforce two or more factor identification such as checking a number, name and date of birth or address. At first thought this would seem to reduce risk, but asking people to perform repetitive actions which consume extra time, may lead to reduced concentration or a mechanical approach which defeats the primary aim of trying to reduce mismatch errors.  Bar code technology can help but is not a cure all.

How should one check multiple factors? Checking name, number and date of birth correlate from a chart at the end of the bed or a wrist band still do not necessarily remove single points of failure (wrong chart, wristband with errors). Verifying the patient’s name and date of birth by asking directly would seem an obvious approach for mentally competent patients. During a recent in-patient stay, this provides the added benefit of furnishing my 80 year old razor-sharp-witted mother to respond to an enquiry of her date of birth with ‘The same as I told you when you asked me at 0911 this morning, and four times a day every day since I was admitted.’