Personal Continuity and Appropriate Prescribing in Primary Care

Marije T. te Winkel; Birgit A. Damoiseaux-Volman; Ameen Abu-Hanna; Birgit I. Lissenberg-Witte; Rob J. van Marum; Henk J. Schers; Pauline Slottje; Annemarie A. Uijen; Jettie Bont; Otto R. Maarsingh

doi:10.1370/afm.2994

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Figure 1.
Selection of the study population.

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Table 1.

Continuity Measures, Examples, and Calculation

Measure and Examples^{^a}	Calculation
Usual provider of care (this measure is based on the fraction of contacts with a particular family physician) Example A: 6/10 = 0.60 Example B: 6/10 = 0.60
Herfindahl Index (this measure is based on the fraction of contacts with all family physicians) Example A: (6²/10²) + (4²/10²) = 0.52 Example B: (6²/10²) + (3²/10²) + (1²/10²) = 0.46
Bice-Boxerman Index (also known as Continuity of Care Index; this measure is based on the fraction of contacts with all family physicians who had at least several contacts) Example A: [(6 × 5)/(10 × 9)] + [(4 × 3)/(10 × 9)] = 0.47 Example B: [(6 × 5)/(10 × 9)] + [(3 × 2)/(10 × 9)] + [(1 × 0)/(10 × 9)] = 0.40

p = total number of different family physicians; n = total number of contacts with any family physician; n_i = number of contacts with family physician i.
↵a Example A: the patient had 10 contacts, of which 6 were with family physician A and 4 were with family physician B. Example B: the patient had 10 contacts, of which 6 were with family physician A, 3 were with family physician B, and 1 was with family physician C.

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Table 2.

Baseline Characteristics of the Study Population

Characteristic	By Number of Chronic Conditions			Total Population (N = 25,854)
Characteristic	0 to 2 (n = 7,992)	3 or 4 (n = 8,349)	5 to 18 (n = 9,513)	Total Population (N = 25,854)
Male, %	45.5	42.8	38.3	42.0
Age group,^{^a} %
65-69 years	45.5	33.7	22.5	33.2
70-74 years	24.2	24.7	21.9	23.5
75-79 years	13.6	17.0	20.9	17.4
80-84 years	8.1	12.3	17.3	12.8
≥85 years	8.6	12.2	17.4	13.0
Prescriptions over 6 years,^{^b} %
0-4 medications	39.8	13.6	4.1	18.2
5-9 medications	37.5	35.0	17.8	29.4
10-14 medications	15.8	29.1	28.3	24.7
≥15 medications	6.9	22.3	49.8	27.7
Chronic conditions, %
Oncologic disease	16.4	33.1	47.4	33.2
Coronary heart disease	7.1	17.6	36.2	21.2
Psychiatric disease	11.4	14.4	18.1	14.8
Diabetes mellitus	7.6	22.1	36.6	23.0
Usual provider of care, No. (%)^{^c}
Low tertile	2,699 (33.8)	2,871 (34.4)	3,253 (34.2)	8,823 (34.1)
Intermediate tertile	2,598 (32.5)	2,732 (32.7)	3,289 (34.6)	8,619 (33.3)
High tertile	2,695 (33.7)	2,746 (32.9)	2,971 (31.2)	8,412 (32.5)
Bice-Boxerman Index, No. (%)^{^d}
Low tertile	2,766 (34.6)	2,783 (33.3)	3,069 (32.3)	8,618 (33.3)
Intermediate tertile	2,479 (31.0)	2,763 (33.1)	3,376 (35.5)	8,618 (33.3)
High tertile	2,747 (34.4)	2,803 (33.6)	3,068 (32.3)	8,618 (33.3)
Herfindahl Index, No. (%)^{^e}
Low tertile	2,458 (30.8)	2,804 (33.6)	3,356 (35.3)	8,618 (33.3)
Intermediate tertile	2,694 (33.7)	2,733 (32.7)	3,188 (33.5)	8,615 (33.3)
High tertile	2,840 (35.5)	2,812 (33.7)	2,969 (31.2)	8,621 (33.3)
Enlistment,^{^f} mean (SD), y	16.8 (8.7)	17.0 (8.8)	16.8 (8.9)	16.9 (8.8)
Contacts in 6 years, mean (SD)
Total	28.6 (23.0)	43.5 (31.6)	63.8 (49.7)	46.4 (40.1)
With family physician	16.8 (14.6)	24.5 (19.7)	35.4 (29.7)	26.1 (24.0)
PIMs, mean (SD)	1.0 (1.3)	1.8 (1.7)	2.9 (2.3)	2.0 (2.0)
PPOs, mean (SD)	1.1 (1.3)	2.0 (1.8)	3.2 (2.4)	2.2 (2.1)

PIM = potentially inappropriate medication; PPO = potential prescribing omission; START = Screening Tool to Alert doctors to Right Treatment; STOPP = Screening Tool of Older Person’s Prescriptions.
↵a On January 1, 2013.
↵b Based on unique Anatomic Therapeutic Chemical codes from STOPP and START criteria.
↵c Low, 0.12-0.59; intermediate, 0.60-0.79; high, 0.80-1.00.
↵d Low, 0.00-0.41; intermediate, 0.42-0.64; high, 0.65-1.00.
↵e Low, 0.09-0.46; intermediate, 0.47-0.66; high, 0.67-1.00.
↵f On December 31, 2018. Follow-up usually spanned 6 years (2013-2018) unless the patient was partially enlisted elsewhere during this period.

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Table 3.

The 10 Most Frequently Observed PIMs

PIM Description		Percentage of Total PIMs (N = 56,605)^{^a}
1.	Stop benzodiazepines (sedative, may cause reduced sensorium, impair balance)	15.7
2.	Stop benzodiazepines taken for ≥4 weeks (no indication for longer treatment; risk of prolonged sedation, confusion, impaired balance, falls, road traffic accidents; all benzodiazepines should be withdrawn gradually if taken for >4 weeks as there is a risk of causing a benzodiazepine withdrawal syndrome if stopped abruptly)	11.9
3.	Stop drugs likely to cause constipation (eg, antimuscarinic/anticholinergic drugs, oral iron, opioids, verapamil, aluminum antacids) in patients with chronic constipation where nonconstipating alternatives are available (risk of exacerbation of constipation)	5.1
4.	Aspirin, clopidogrel, dipyridamole, vitamin K antagonists, direct thrombin inhibitors, or factor Xa inhibitors with concurrent substantial bleeding risk, that is, uncontrolled severe hypertension, bleeding diathesis, recent nontrivial spontaneous bleeding (high risk of bleeding)	4.6
5.	Stop PPI for uncomplicated peptic ulcer disease or erosive peptic esophagitis at full therapeutic dosage for >8 weeks (dose reduction or earlier discontinuation indicated)	4.5
6.	Stop colchicine if eGFR <10 mL/min/1.73m² (risk of colchicine toxicity)	4.0
7.	Stop NSAIDs if eGFR <50 mL/min/1.73m² (risk of deterioration in renal function)	3.6
8.	Stop use of oral or transdermal strong opioids (morphine, oxycodone, fentanyl, buprenorphine, diamorphine, methadone, tramadol, pethidine, pentazocine) as first-line therapy for mild pain (WHO analgesic ladder not observed)	3.5
9.	Stop neuroleptic drugs (may cause gait dyspraxia, parkinsonism)	3.2
10.	Stop hypnotic Z-drugs such as zopiclone, zolpidem, zaleplon (may cause protracted daytime sedation, ataxia)	3.2

eGFR = estimated glomerular filtration rate; NSAID = nonsteroidal anti-inflammatory drug; PIM = potentially inappropriate medication; PPI = proton pump inhibitor; WHO = World Health Organization.
Note: PIMs provide information on correct deprescribing according to the Screening Tool of Older Person’s Prescriptions (STOPP) criteria.
↵a Unique PIMs per patient over 6 years.

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Table 4.

The 10 Most Frequently Observed PPOs

PPO Description		Percentage of Total PPOs (N = 55,578)^{^a}
1.	Start laxatives in patients receiving opioids regularly	14.7
2.	Start ACE inhibitor with systolic heart failure and/or documented coronary artery disease	7.9
3.	Start statin therapy with a documented history of coronary, cerebral, or peripheral vascular disease, unless patient has end-of-life status or is >85 years old	7.4
4.	Start ACE inhibitor or ARB (if intolerant of ACE inhibitor) in diabetes with evidence of renal disease, that is, dipstick proteinuria or microalbuminuria (>30 mg/24 hours) with or without serum biochemical renal impairment	7.1
5.	Start metformin twice a day with diabetes mellitus type 2 if eGFR is 30-50 mL/min/1.73m², not if < 30 mL/min/1.73m²	6.5
6.	Start antiplatelet therapy (aspirin, clopidogrel, prasugrel, or ticagrelor) with a documented history of coronary, cerebral, or peripheral vascular disease	5.9
7.	Start aspirin (75-160 mg once daily) in the presence of chronic atrial fibrillation, where vitamin K antagonists or direct thrombin inhibitors or factor Xa inhibitors are contraindicated	5.6
8.	Start β-blocker with ischemic heart disease	5.1
9.	Start vitamin D supplement in older adults who are housebound, are experiencing falls, or have osteopenia (bone mineral density T-score is greater than −2.5 but less than −1.0 in multiple sites)	4.9
10.	Start regular inhaled β₂ agonist or antimuscarinic bronchodilator (eg, ipratropium, tiotropium) for mild to moderate asthma or COPD	4.8

ACE = angiotensin-converting enzyme; ARB = angiotensin receptor blocker; COPD = chronic obstructive pulmonary disease; eGFR = estimated glomerular filtration rate; PPO = potential prescribing omission.
Note: PPOs provide information on correct prescribing according to the Screening Tool to Alert doctors to Right Treatment (START) criteria.
↵a Unique PPOs per patient over 6 years.

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Table 5.

Adjusted Associations Between Personal Continuity Measures and Incident PPO

Continuity Measure	RR (95% CI) for PPO	P Value
Usual provider of care		<.001
Low tertile	ref
Intermediate tertile	0.96 (0.94-0.99)
High tertile	0.91 (0.89-0.94)
Bice-Boxerman Index		<.001
Low tertile	ref
Intermediate tertile	1.00 (0.97-1.02)
High tertile	0.93 (0.90-0.96)
Herfindahl Index		<.001
Low tertile	ref
Intermediate tertile	0.95 (0.92-0.98)
High tertile	0.88 (0.86-0.91)

PPO = potential prescribing omission; ref = reference category; RR = rate ratio.
Notes: Results of multilevel negative binomial regression analysis with adjustment for sex, age, and number of chronic conditions. The RRs are exponential regression coefficients.
Total population was 25,854.

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Table 6.

Adjusted Associations Between Personal Continuity Measures and Incident PIM

Continuity Measure	0-2 Chronic Conditions		3-4 Chronic Conditions		5-18 Chronic Conditions		Total Population
Continuity Measure	RR (95% CI) for PIM	P Value	RR (95% CI) for PIM	P Value	RR (95% CI) for PIM	P Value	RR (95% CI) for PIM	P Value
Usual provider of care		.002		.44		<.001		<.001
Low tertile	ref		ref		ref		ref
Intermediate tertile	1.12 (1.05-1.18)		0.97 (0.92-1.03)		0.94 (0.91-0.98)		0.97 (0.94-1.00)
High tertile	1.04 (0.98-1.12)		0.96 (0.92-1.02)		0.90 (0.87-0.94)		0.92 (0.89-0.95)
Bice-Boxerman Index		<.001		.21		.002		<.001
Low tertile	ref		ref		ref		ref
Intermediate tertile	1.23 (1.16-1.31)		1.05 (0.99-1.10)		0.99 (0.95-1.03)		1.07 (1.04-1.10)
High tertile	1.13 (1.06-1.20)		1.01 (0.96-1.07)		0.93 (0.90-0.97)		0.99 (0.95-1.02)
Herfindahl Index		.04		.01		<.001		<.001
Low tertile	ref		ref		ref		ref
Intermediate tertile	1.01 (0.95-1.08)		0.96 (0.91-1.01)		0.92 (0.89-0.96)		0.92 (0.89-0.94)
High tertile	0.94 (0.88-1.00)		0.92 (0.87-0.97)		0.87 (0.83-0.90)		0.85 (0.82-0.88)

PIM = potentially inappropriate medication; ref = reference category; RR = rate ratio.
Notes: Results of multilevel negative binomial regression analysis adjusted for sex and age, and stratified by number of chronic conditions. The RRs are exponential regression coefficients. Total population was 25,854; there were 7,992 patients with 0-2 chronic conditions, 8,349 patients with 3-4 chronic conditions, and 9,513 patients with 5-18 chronic conditions.