Static outliers for The Cambridge Practice

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 The Cambridge Practice is higher than most

BNF Chemical	Chemical Items	BNF Subparagraph	Subparagraph Items	Ratio	Mean	std	Z_Score	Plots
Timolol with diuretic☰	2	Beta-adrenoceptor blocking drugs	4235	0.00	0.00	0.00	32.06
Timolol 10mg / Bendroflumethiazide 2.5mg tablets : 2
Olanzapine embonate☰	4	Antipsychotic depot injections	46	0.09	0.00	0.01	8.39
Olanzapine embonate 300mg inj vials : 4
Econazole nitrate☰	28	Vaginal and vulval infections	105	0.27	0.01	0.03	7.93
Econazole 1% cream : 4 Econazole 150mg pessaries : 24
Diclofenac sodium☰	1	Ocular diagnostic & peri-operative prepn & photodynamic tt	1	1.00	0.03	0.13	7.71
Diclofenac 0.1% eye drops : 1
Testosterone undecanoate☰	86	Male sex hormones and antagonists	440	0.20	0.03	0.03	5.23
Nebido 1000mg/4ml solution for injection vials : 58 Testosterone undecanoate 1g/4ml solution for injection vials : 28

Prescribing where The Cambridge Practice is lower than most

BNF Chemical	Chemical Items	BNF Subparagraph	Subparagraph Items	Ratio	Mean	std	Z_Score	Plots
Clotrimazole☰	67	Vaginal and vulval infections	105	0.64	0.90	0.10	-2.73
Clotrimazole 10% vaginal cream : 2 Canesten Combi 500mg Soft Gel pessary and 2% cream : 1 Clotrimazole 500mg pessary and Clotrimazole 2% cream : 26 Clotrimazole 500mg pessaries : 16 Clotrimazole 2% cream : 16 Clotrimazole 200mg pessaries : 6
Baclofen☰	110	Skeletal muscle relaxants	257	0.43	0.83	0.18	-2.16
Baclofen 10mg tablets : 99 Baclofen 5mg/5ml oral solution sugar free : 6 Lyflex 5mg/5ml oral solution : 5
Cetirizine hydrochloride☰	61	Antihistamines	1133	0.05	0.28	0.11	-2.13
Cetirizine 10mg tablets : 34 Cetirizine 1mg/ml oral solution sugar free : 27
Finasteride☰	277	Male sex hormones and antagonists	440	0.63	0.82	0.12	-1.65
Finasteride 5mg tablets : 277
Loratadine☰	27	Antihistamines	1133	0.02	0.12	0.06	-1.53
Loratadine 5mg/5ml oral solution : 7 Loratadine 10mg tablets : 20