*MEDICINE* Oral prednisolone use in asthma

[brianmackenna]

I have created an oral pred notebook here of medicines codes. We now need to apply a rule on it to suit inclusion/variable criteria.

[brianmackenna]

NHS Digital have included prednisolone in their definition of severe asthma in their shielding criteria rules

Patients with asthma were identified as being prescribed Long acting beta2-agonist (LABA) as either a LABA or in combination with an inhaled corticosteroid (LABA/ICS) OR prescriptions for a leukotriene receptor antagonist (e.g. monteluekast).
AND
From the above list of patients, those who had been dispensed 4 or more prescriptions for prednisolone between July 2019 and December 2019 were identified and considered to have severe asthma.

4 prescriptions in 6 months moves it into every month repeat prescription therapy. Shall we set a maximum threshold or leave as any prescription for oral steroid? (probably 4 per year)

[brianmackenna]

Discussed on Slack and we think NHSD definition is too permissive and will include regular ongoing oral prednisolone which may be used for other conditions. W will look at distinct dates of issue as sometimes pred can be made up with different tablet stregths.

DEFINITION: Up to a maximum of four distinct dates or oral prednisolone issued in the past 12 months.

CODE LISTS: Oral pred csv

FLEXIBILITY NEEDED BETWEEN STUDIES:
EFFECTS ON COHORT SELECTION:

POTENTIAL BIASES:

CLINICAL SIGN OFF & DATE: @brianmackenna 25/4

EPIDEMIOLOGY SIGN OFF & DATE: @ianjdouglas 01/05/2020

SHARED WITH WIDER TEAM:

FINAL SIGN OFF DATE (and apply label)

[alexwalkerepi]

Draft of the new asthma definition:

    asthma=patients.categorised_as(
        {
            "0": "DEFAULT",
            "1": """
                (
                  recent_asthma_code OR (
                    asthma_code_ever AND NOT copd_code_ever AND (
                      recent_salbutamol_count >= 3 OR recent_ics
                    )
                  )
                  AND NOT prednisolone_last_year >= 1 AND NOT prednisolone_last_year <= 4
                )
            """,
            "2": """
                (
                  recent_asthma_code OR (
                    asthma_code_ever AND NOT copd_code_ever AND (
                      recent_salbutamol_count >= 3 OR recent_ics
                    )
                  )
                  AND prednisolone_last_year >= 1 AND prednisolone_last_year <= 4
                )
            """,
        },
        recent_asthma_code=patients.with_these_clinical_events(
            asthma_codes,
            between=['2018-02-01', '2020-02-01'],
        ),
        asthma_code_ever=patients.with_these_clinical_events(asthma_codes),
        copd_code_ever=patients.with_these_clinical_events(chronic_respiratory_disease_codes),
        recent_salbutamol_count=patients.with_these_medications(
            salbutamol_codes,
            between=['2018-02-01', '2020-02-01'],
            returning="number_of_matches_in_period",
        ),
        recent_ics=patients.with_these_medications(
            ics_codes,
            between=['2018-02-01', '2020-02-01'],
        ),
        prednisolone_last_year=patients.with_these_medications(
            prednisolone_codes,
            between=['2019-02-01', '2020-02-01'],
            returning="number_of_matches_in_period",
        ),
    ),

[brianmackenna]

https://codelists.opensafely.org/codelist/opensafely/asthma-oral-prednisolone-medication/