Relationship between prescribing of antibiotics and other medicines in primary care: a cross-sectional study

Yan Li; Anna Mölter; Andrew White; William Welfare; Victoria Palin; Miguel Belmonte; Darren M Ashcroft; Matthew Sperrin; Tjeerd Pieter van Staa

doi:10.3399/bjgp18X700457

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Figure 1.
Associations between rates of prescribing of antibiotics and other medicines in general practices. CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data.
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Figure 2.
Associations between rates of prescribing of antibiotics and non-opioid painkillers in general practices.
CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data.
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Figure 3.
Associations between rates of prescribing of antibiotics and benzodiazepines in general practices. CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data.

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Table 1.

Baseline characteristics of NHS-DPPD and CPRD practices

Baseline characteristics of practices	NHS-DPPD (n= 6517)	CPRD (n= 587)
List per full-time equivalent GP, mean (SD)	2306.2 (12114.0)	n/a^a
Percentage of patients in London	5.7	12.8
Percentage of patients in North of England	49.7	54.3
Percentage of patients in South of England	44.6	32.9
Practice list size, mean (SD)	7558.0 (4194.8)	7732.2 (3516.3)
Index of Multiple Deprivation 2015 score, mean (SD)	25.9 (17.4)	n/a^a
Adult skills sub-domain deprivation score, mean (SD)	0.3 (0.1)	n/a^a
Health deprivation and disability score, mean (SD)	0.2 (0.9)	n/a^a
Percentage of female patients, mean (SD)	50.0 (2.2)	58.1 (2.1)
Rate of prescribing of other medicines, mean (SD)^b	17 631.3 (5707.8)	16 587.3 (5923.6)
Rate of prescribing of antibiotics, mean (SD)^b	576.1 (148.1)	578.9 (177.4)
Rate of prescribing of non-opioid painkillers, mean (SD)^b	1211.4 (544.4)	1365.7 (611.3)
Rate of prescribing of benzodiazepines, mean (SD)^b	274.8 (162.4)	325.1 (247.1)

↵a n/a means the dataset does not have the variable.
↵b Rate per 1000 patients per year. CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data. n/a = not applicable. SD = standard deviation.

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Table 2.

Associations of prescribing of antibiotics with that of other medicines, non-opioid painkillers, and benzodiazepines

Risk factor	Mean (SD)	5th	Percentile of risk factors			Change in risk factor		Rate of antibiotics		Rate of antibiotics		% Increase in antibiotic for 5th–95th^c
Risk factor	Mean (SD)	5th	25th	75th	95th	IQR	5th–95th	Change per IQR,^b crude (95% CI)	Change per IQR, adjusted (95% CI)	Change per 5th–95th percentile,^b crude (95% CI)	Change per 5th–95th percentile,^b adjusted (95% CI)	Crude	Adjusted
Antibiotics^a
NHS-DPPD	576.1 (148.1)	329.9	486.9	666.8	808.7	179.9	478.8	n/a	n/a	n/a	n/a	n/a	n/a
CPRD	578.9 (177.4)	268.0	488.1	688.5	852.4	200.4	584.4	n/a	n/a	n/a	n/a	n/a	n/a
Other medicines^a
NHS-DPPD	17 631.3 (5707.8)	8815.9	13 588.0	21 411.6	27 159.8	7823.6	18 343.9	141.8 (138.3 to 145.3)	117.8 (113.2 to 122.5)	332.5 (324.4 to 340.7)	276.3 (265.4 to 287.2)	80	60
CPRD	16 587.3 (5923.6)	6909.8	12 732.6	20 399.0	25 966.7	7666.4	19 056.8	167.5 (152.2 to 182.9)	162.8 (148.4 to 177.3)	416.4 (378.3 to 454.5)	404.8 (368.9 to 440.6)	100	100
Non-opioid painkillers^a
NHS-DPPD	1211.4 (544.4)	462.9	809.6	1531.3	2215.6	721.7	1752.7	128.5 (124.8 to 132.2)	119.7 (114.5 to 124.9)	312.0 (303.1 to 321.0)	290.7 (278.0 to 303.4)	70	60
CPRD	1365.7 (611.3)	463.4	895.0	1757.8	2344.3	862.8	1880.9	189.5 (173.0 to 206.0)	189.0 (172.1 to 206.0)	413.1 (377.0 to 449.1)	412.1 (375.3 to 449.0)	100	100
Benzodiazepines^a
NHS-DPPD	274.8 (162.4)	79.7	167.8	344.3	567.3	176.5	487.6	90.7 (87.0 to 94.5)	62.4 (58.9 to 66.0)	250.6 (240.4 to 260.9)	172.4 (162.6 to 182.2)	50	30
CPRD	325.1 (247.1)	81.2	180.0	381.0	774.9	201.0	693.7 (87.0 to 110.5)	98.7 (81.1 to 104.4)	92.7 (300.1 to 381.2)	340.7 (279.8 to 360.1)	320.0	60	50

↵a Per 1000 patients per year.
↵b Change in rate of antibiotic prescribing over IQR or 5^th to 95^th percentile of risk factor (other medicines, painkillers, or benzodiazepines).
↵c % Increase in antibiotic for 5th–95% was calculated using Poisson model. CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data. n/a = not applicable. IQR = interquartile range.

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Table 3.

Analysis of relative importance of continuous risk factors for antibiotic prescribing

Risk factors	Change in rate of antibiotics (95% CI)^a over 5th to 95th percentiles in risk factor^b
	NHS-DPPD
Rate of prescribing of other medicines	276.3 (265.4 to 287.2)
Adult skills sub-domain score in practice area	74.2 (57.8 to 90.5)
% Male patients aged 0–4 years in practice	48.5 (32.4 to 64.6)
% Female patients aged 80–85 years in practice	41.2 (29.4 to 52.9)
Practice score in overall experience of making an appointment: not good	28.7 (14.0 to 43.4)
Health deprivation and disability score in practice area	23.5 (5.3 to 41.8)
% Male patients aged 5–9 years in practice	25.0 (9.0 to 40.9)
% Patients in practice with arthritis or long-term joint problem	20.3 (9.1 to 31.5)
% Female patients aged 45–49 years in practice	21.5 (9.6 to 33.5)
Crime score in practice area	16.0 (3.8 to 28.2)
% Male patients aged 55–59 years in practice	16.9 (2.5 to 31.2)
Medical conditions — % none of these conditions	13.9 (1.1 to 26.6)
% Patients in practice with another long-term condition	11.5 (2.5 to 20.6)
QOF asthma achievement, %	−5.8 (−10.6 to −1.0)
Practice score in rating of GP involving patients in decisions about care: % good	−12.8 (−21.2 to −4.3)
Indoors sub-domain score in practice area	−13.4 (−22.2 to −4.5)
Outdoors sub-domain score in practice area	−16.2 (−28.6 to −3.9)
Practice score in last seen or spoke to a GP: over the past 3 months	−17.3 (−26.0 to −8.6)
Practice score in confidence and trust in GP: % no, not at all	−22.2 (−32.8 to −11.6)
% Male patients aged 40−44 years in practice	−25.1 (−35.8 to −14.4)
Practice score of last time wanted to see GP or nurse: not seen GP at surgery	−23.3 (−31.5 to −15.0)
Practice score of overall experience of GP surgery: not good	−24.9 (−41.1 to −8.7)
Income deprivation score in practice area affecting older people	−42.5 (−58.6 to −26.4)
Employment score in practice area	−51.5 (−71.3 to −31.8)
	CPRD
Rate of prescribing of other medicines	404.8 (368.9 to 440.6)
Rate of consultations for upper respiratory tract infections	43.8 (9.3 to 78.3)
% Patients in practice who are smokers	−41.9 (−79.3 to −4.5)
Duration of GP visit, mean	−60.9 (−95.9 to −25.8)
% Patients in practice with higher Charlson comorbidity index	−71.7 (−108.3 to −35.2)

↵a Per 1000 patients per year.
↵b Change in rate of antibiotic prescribing comparing practices in lower (5^th) with higher percentiles (95^th) of the risk factor. CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data. QOF = Quality and Outcomes Framework.

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Table 4.

Explorative analyses of medication classes that are correlated with antibiotic prescribing^a

Risk factor — type of medicines (BNF category)	Change in rate of antibiotics (95% CI)^b over 5th to 95th percentiles in risk factor^c
Risk factor — type of medicines (BNF category)	NHS-DPPD, crude (95% CI)	CPRD, crude (95% CI)
Proton pump inhibitors (1.3.5)	316.0 (307.5 to 324.5)	406.1 (365.4 to 446.8)
Renin–angiotensin system drugs (2.5.5)	287.1 (277.7 to 296.5)	312.7 (263.2 to 362.3)
Antiplatelet drugs (2.9)	283.2 (273.9 to 292.6)	346.4 (300.1 to 392.7)
Drugs used in nausea and vertigo (4.6)	335.6 (326.7 to 344.5)	258.9 (220.8 to 297.0)
Selective serotonin reuptake inhibitors (4.3.3)	332.6 (323.7 to 341.4)	402.7 (363.2 to 442.2)
Corticosteroids (respiratory) (3.2)	323.4 (314.3 to 332.5)	263.2 (214.4 to 311.9)
Antispasmodic and other drugs altering gut motility (1.2)	301.3 (291.4 to 311.2)	299.0 (253.8 to 344.1)
Glucocorticoid therapy (6.3.2)	322.0 (312.8 to 331.3)	158.3 (110.5 to 206.1)
Beta-adrenoceptor blocking drugs (2.4)	301.1 (292.1 to 310.1)	363.0 (317.5 to 408.5)
Lipid-regulating drugs (2.12)	287.9 (278.6 to 297.1)	189.2 (138.7 to 239.7)

↵a Table shows the top 10 largest associations in NHS-DPPD, with corresponding results in CPRD.
↵b Per 1000 patients per year.
↵c Change in rate of antibiotic prescribing comparing practices in lower (5th) with higher (95th) percentiles of the risk factor. BNF = British National Formulary. CPRD = Clinical Practice Research Datalink. DPPD = digital practice prescribing data. IQR = interquartile range.