Static outliers for Open Door

There is substantial variation in prescribing behaviours, across various different areas of medicine. Some variation can be explained by demographic changes, or local policies or guidelines, but much of the remaining variation is less easy to explain. At OpenPrescribing we are piloting a number of data-driven approaches to identify unusual prescribing and collect feedback on this prescribing to inform development of new tools to support prescribers and organisations to audit and review prescribing.

This report has been developed to automatically identify prescribing patterns at a chemical level which are furthest away from “typical prescribing” and can be classified as an “outlier”. We calculate the number of prescriptions for each chemical in the BNF coding system using the BNF subparagraph as a denominator, for prescriptions dispensed between April 2021 and August 2021. We then calculate the mean and standard deviation for each numerator and denominator pair across all practices/CCGs/PCNs/STPs. From this we can calculate the “z-score”, which is a measure of how many standard deviations a given practice/CCG/PCN/STP is from the population mean. We then rank your “z-scores” to find the top 5 results where prescribing is an outlier for prescribing higher than its peers and those where it is an outlier for prescribing lower than its peers.

It is important to remember that this information was generated automatically and it is therefore likely that some of the behaviour is warranted. This report seeks only to collect information about where this variation may be warranted and where it might not. Our full analytical method code is openly available on GitHub here.

The DataLab is keen to hear your feedback on the results. You can do this by completing the following survey or emailing us at ebmdatalab@phc.ox.ac.uk. Please DO NOT INCLUDE IDENTIFIABLE PATIENT information in your feedback. All feedback is helpful, you can send short or detailed feedback.

Prescribing where Open Door is higher than most

BNF Chemical	Chemical Items	BNF Subparagraph	Subparagraph Items	Ratio	Mean	std	Z_Score	Plots
Liothyronine sodium☰	6	Thyroid hormones	130	0.05	0.00	0.00	15.88
Liothyronine 20microgram tablets : 6
Latanoprost and timolol☰	5	Treatment of glaucoma	11	0.45	0.03	0.03	14.48
Xalacom eye drops : 5
Celecoxib☰	162	Non-steroidal anti-inflammatory drugs	350	0.46	0.03	0.04	11.93
Celecoxib 100mg capsules : 162
Benzoyl peroxide☰	5	Topical preparations for acne	6	0.83	0.08	0.07	10.37
Benzoyl peroxide 5% gel : 5
Metformin hydrochloride/pioglitazone☰	16	Other antidiabetic drugs	390	0.04	0.00	0.00	8.73
Pioglitazone 15mg / Metformin 850mg tablets : 16

Prescribing where Open Door is lower than most

BNF Chemical	Chemical Items	BNF Subparagraph	Subparagraph Items	Ratio	Mean	std	Z_Score	Plots
Levothyroxine sodium☰	124	Thyroid hormones	130	0.95	1.00	0.00	-15.39
Levothyroxine sodium 25microgram tablets : 29 Levothyroxine sodium 50microgram tablets : 57 Levothyroxine sodium 100microgram tablets : 38
Bisoprolol fumarate☰	279	Beta-adrenoceptor blocking drugs	723	0.39	0.65	0.08	-3.32
Bisoprolol 5mg tablets : 61 Bisoprolol 2.5mg tablets : 111 Bisoprolol 1.25mg tablets : 75 Bisoprolol 3.75mg tablets : 22 Bisoprolol 10mg tablets : 5 Bisoprolol 7.5mg tablets : 5
Desogestrel☰	35	Oral progestogen-only contraceptives	45	0.78	0.94	0.05	-2.96
Desogestrel 75microgram tablets : 31 Cerazette 75microgram tablets : 1 Cerelle 75microgram tablets : 3
Lidocaine hydrochloride☰	5	Local anaesthetics	10	0.50	0.91	0.14	-2.93
Lidocaine 20mg/2ml (1%) solution for injection ampoules : 2 Emla 5% cream : 2 Instillagel gel : 1
Naproxen☰	137	Non-steroidal anti-inflammatory drugs	350	0.39	0.69	0.10	-2.93
Naproxen 250mg tablets : 64 Naproxen 500mg tablets : 56 Naproxen 500mg gastro-resistant tablets : 17