*DISEASE* Myocardial infarction

[CarolineMorton]

For study on NSAIDs.

Read 2 code list:
Myocardial_infarction_lshtm.xlsx

We now need snowmed and qof codes

QoF codes attached here MI QoF.xlsx Includes duplicated ctv3 codes where they appear in different clusterids

Snomed MI codes Snomed MI.xlsx

[HenryDrysdale]

Hi,

I've reviewed the MI read 3 codes from TPP. A couple of things to note:

1. I've excluded codes for "Raised cardiac enzymes", because that doesn't neccesarily mean MI.
2. Q waves are caused by MI, so I've left them all in.

Henry

MI_CTV3_Raw_HD.xlsx

[CarolineMorton]

FINAL SIGN OFF

DEFINITION: Patients who have any myocardial infarction Read 3 code ever on their medical records held by TPP. Absence of a code on the record is taken as no history of myocardial infarction.

Example output:	patient_id	condition	date
123	Myocardial infarction	1/2/2009
332	ECG: lateral infarction	2/4/2016

CODE LISTS: Read 3 code list - FINAL code list: MI_CTV3_final.xlsx

Created using this method by TPP:

1. Read 2 LSHTM code list compiled by @ianjdouglas Myocardial_infarction_lshtm.xlsx

2. Adding in key clusters from QOF and mapping to CTV3 - added by @ianjdouglas. MI QoF.xlsx Includes duplicated ctv3 codes where they appear in different clusterids

3. Adding in high level snowmed codes and mapping to CTV3. Added by @ianjdouglas. Snomed MI.xlsx

4. Final list sense checked by clinician (Checked by @HenryDrysdale). MI_CTV3_Raw_HD.xlsx

   • I've excluded codes for "Raised cardiac enzymes", because that doesn't neccesarily mean MI.
   • Q waves are caused by MI, so I've left them all in.

• FLEXIBILITY NEEDED BETWEEN STUDIES: We may want to restrict to patients with certain medications, or who have had MI in the last year as treatment may be different
• EFFECTS ON COHORT SELECTION: None

POTENTIAL BIASES: Diagnosed in hospital so may not be on record, but overall this is less likely as given medications from primary care usually for at least the first year.

CLINICAL SIGN OFF & DATE: Henry Drysdale 15/04/20

EPIDEMIOLOGY SIGN OFF & DATE:

SHARED WITH WIDER TEAM: Yes

FINAL SIGN OFF DATE (and apply label)

[ianjdouglas]

@CarolineMorton and @HenryDrysdale - quick question on these. In 4. Final list... are we happy with codes at lines: 62 (Angina:[cresc][unstabl][at rest])(preinfar syn)(imp infarc)
96 (Silent myocardial ischaemia)?

[HenryDrysdale]

@ianjdouglas

Yes I'm happy with those. Unstable angina is an "acute coronary syndrome", so treated the same way as some MIs. Patients with "silent myocardial ischaemia" haven't neccesarily had an MI, but are likely to be on an antiplatelet.

@CarolineMorton does that seem reasonable?

[ianjdouglas]

Thanks @HenryDrysdale - that's useful to know as we didn't include any other unstable angina or myocardial ischaemia terms (there are several for both!). We'll either need to add them in, or decide to exclude them all. About to have a call, so can discuss then.

[HenryDrysdale]

@ianjdouglas I see - very sorry if I'm confusing things!

[ianjdouglas]

@HenryDrysdale Not at all! Much better to be clear about what we're trying to identify with the variable and making sure we've defined it so we're all happy it does the job

[CarolineMorton]

I think we should exclude as although it represents ACS and is ischaemia, it needs better confirmation and i suspect is put on without a definite diagnosis. For example you might send someone to hospital with unstable angina and code it that way. That's just a feeling.

For ian's point, i think we also should not include as we should then include all syndromes under ACS as well, rather than MI plus unstable angina as I am sure the code unstable angina also has other codes which have not been included.

[ianjdouglas]

Meeting note: 16/04/2020 - it was decided not to use MI as a criterion for exclusion, under the assumption that the vast majority of aspirin users with a histor of MI would either a) be identified as users of aspirin by prescribing or QoF codes, or b) not be prescribed another NSAID simultaneously, and so the number likely included in the NSAID cohort would be very small, if any