A National Survey of Attitudes and Practices of Physicians Relating to Therapeutic Drug Monitoring and Clinical Pharmacokinetic Service: Strategies for Enhancing Patient’s Care in Saudi Arabia

Figures & data

Table 1 Demographic Characteristics of the Physicians

	Consultant n (%)	GP n (%)	Resident n (%)	p-value
Age group (years) (n=699)
≤ 39	88 (25.43)	225 (69.7)	30 (100.0)	<0.0001^a
40–49	133 (38.44)	62 (19.2)	–
≥ 50	125 (36.13)	36 (11.1)	–
Gender (n=723)
Male	291 (80.4)	236 (71.3)	13 (43.3)	<0.0001^b
Female	71 (19.6)	95 (28.7)	17 (56.7)
Workplace (n=723)
Specialist Hospital	127 (35.0)	87 (26.3)	16 (53.3)	<0.0001^b
Primary Care Hospital	189 (52.1)	218 (65.9)	10 (33.3)
Clinic/Health Center	37 (10.2)	17 (5.1)	–
Others (eg, infirmaries)	10 (2.8)	9 (2.7)	4 (13.3)
Total years of experience (n=720)
< 10	65 (17.9)	170 (52.0)	22 (73.3)	<0.0001^b
10–15	89 (24.5)	94 (28.7)	8 (26.7)
16–20	65 (17.9)	21 (6.4)	–
> 20	144 (39.7)	42 (12.8)	–
Employment in current workplace (years) (n=711)
< 10	161 (45.1)	226 (69.8)	20 (66.7)	<0.0001^b
10–15	79 (22.1)	64 (19.8)	9 (33.3)
16–20	41 (11.5)	10 (3.1)	1 (3.3)
> 20	76 (21.3)	24 (7.4)	–

Notes: ^aFisher’s exact test. ^bChi-square test.

Table 2 Physicians’ Specialties

Specialty	Consultant	GP	Resident
	n (%)	n (%)	n (%)
Internal Medicine	107 (29.6)	93 (28.0)	6 (20.0)
Cardiology	14 (13.1)	14 (15.1)	–
Endocrinology	10 (9.3)	4 (4.3)	1 (16.7)
Gastroenterology	16 (15.0)	12 (12.9)	–
Hematology	7 (6.5)	–	–
Infectious disease	6 (5.6)	1 (1.1)	1 (16.7)
Nephrology	6 (5.6)	7 (7.5)	–
Oncology	8 (7.5)	6 (6.5)	–
Rheumatology	3 (2.8)	3 (3.2)	1 (16.7)
Others (not specified)	37 (34.6)	46 (49.5)	3 (50.0)
Ophthalmology	13 (3.6)	7 (2.1)	–
Pediatrics	54 (14.9)	31 (9.4)	4 (13.3)
Urology	13 (3.6)	5 (1.5)	–
Obstetrics/Gynecology	21 (5.8)	15 (4.6)	–
Orthopedics	10 (2.8)	15 (4.6)	2 (6.7)
Family Medicine	20 (5.5)	42 (12.8)	1 (3.3)
Neurology	12 (3.3)	1 (0.3)	1 (3.3)
Surgery	45 (12.4)	39 (11.9)	7 (23.3)
Psychiatry	11 (3.0)	1 (0.3)	–
Ears, Nose and Throat (E.N.T)	13 (3.6)	9 (2.7)	1 (3.3)
Osteopathic Physician	–	1 (0.3)	–
Dermatology	8 (2.2)	6 (1.8)	–
Others (not specified)	35 (9.7)	65 (19.8)	8 (26.7)

Table 3 Prescriber Knowledge About PK/TDM

Category	Consultant	GP	Resident	p-value
	n (%)	n (%)	n (%)
PK-TDM course taken
Undergraduate level	200 (55.1)	128 (38.7)	18 (60.0)	0.037
Postgraduate level	76 (20.9)	16 (4.8)	3 (10.0)	<0.001
Continuing education	56 (15.4)	26 (7.9)	2 (6.7)	0.005
Self-study	41 (12.7)	27 (14.2)	2 (6.7)	0.195
PK/TDM parameters checked when prescribing or modifying a drug dose
Plasma concentration	212 (58.4)	141 (42.6)	14 (46.7)	<0.001
Drug clearance	137 (37.7)	102 (30.8)	14 (46.7)	0.063
Half-life	199 (54.8)	150 (45.3)	17 (56.7)	0.035
Rate of metabolism	78 (21.5)	51 (15.4)	4 (13.3)	0.091
Drug excretion in urine	124 (34.2)	93 (28.1)	6 (20.0)	0.095
Volume of distribution	64 (17.6)	30 (9.1)	4 (13.3)	0.004
Check organ function before prescribing a drug?
I never do this	9 (2.5)	20 (6.0)	2 (6.7)	0.055
Only kidney function	123 (33.9)	103 (31.1)	14 (46.7)	0.204
Only liver function	103 (28.4)	81 (24.5)	13 (43.3)	0.066
Always both	112 (30.9)	101 (30.5)	10 (33.3)	0.950
Only for certain drugs	89 (24.5)	66 (19.9)	8 (26.7)	0.303
Only for certain diseases	147 (40.5)	138 (41.7)	11 (36.7)	0.847

Table 4 Prescriber Knowledge About Medication Classes Used in PK/TDM

Category	Consultant	GP	Resident	p-value
	n (%)	n (%)	n (%)
Medication classes for which physicians used the PK/TDM laboratory
Antibiotics	177 (26.9)	135 (24.4)	20 (25.6)
Antiepileptics	152 (23.1)	127 (22.9)	16 (20.5)
Antiarrhythmics	108 (16.4)	108 (19.5)	12 (15.4)
Immunosuppressants	62 (9.4)	57 (10.3)	10 (12.8)
Antimanics	50 (7.6)	57 (10.3)	5 (6.4)
Antineoplastics	40 (6.1)	26 (4.7)	6 (7.7)
Bronchodilators	38 (5.8)	29 (5.2)	4 (5.1)
Others	30 (4.6)	15 (2.7)	5 (6.4)
Reference information for prescribing a dose
Hospital/Clinical pharmacist	192 (53.0)	153 (47.1)	18 (60.0)	0.171
Past experience	122 (34.0)	112 (35.4)	7 (24.1)	0.466
PDR	118 (32.8)	96 (30.2)	1 (3.4)	0.004
Scientific literature	108 (30.1)	53 (16.7)	2 (6.9)	<0.001
LEXI-COM online	97 (26.9)	90 (28.1)	3 (10.3)	0.117
Clin. Pharmacol. database	94 (26.1)	84 (26.4)	5 (17.2)	0.553
LEXI-COM book	46 (12.9)	37 (11.8)	-	0.118
Rx-List.com	19 (5.3)	19 (6.0)	1 (3.4)	0.815
Facts & Comparisons	14 (3.9)	16 (5.0)	2 (6.9)	0.466
Other compendia	61 (17.4)	58 (18.4)	14 (46.7)	<0.001

Table 5 Basis for Dose Adjustment

Category	Consultant	GP	Resident	p-value
	n (%)	n (%)	n (%)
I consult with clinical pharmacist	205 (56.9)	175 (53.7)	18 (60.0)	0.611
I consult standard references	176 (49.3)	163 (50.9)	12 (41.4)	0.600
I use evidence-based medicine	168 (47.1)	144 (44.6)	12 (41.4)	0.724
I use my experience	150 (41.9)	119 (37.8)	8 (27.6)	0.226
I use PK principles	140 (38.9)	100 (31.9)	7 (24.1)	0.076
I consult with colleagues	96 (27.1)	118 (36.9)	9 (31.0)	0.025
I comply with patient request	9 (2.5)	18 (5.8)	2 (6.9)	0.086
I usually do one or more of the following:
I change the dose (increase or decrease) when there is no adequate response to the drug	211 (58.1)	210 (63.4)	14 (46.7)	0.111
I use evidence-based medicine principles for drug therapy	182 (50.1)	144 (43.5)	9 (30.0)	0.041
I add another drug to assist the pharmacologic response	170 (46.8)	159 (48.0)	10 (33.3)	0.303
I order the determination of drug level in plasma or blood when I suspect high or toxic levels	156 (43.0)	133 (40.2)	15 (50.0)	0.502
I change the dosing interval of the drug (frequency of administration)	154 (42.4)	138 (41.7)	11 (36.7)	0.825
I change medication altogether and switch the patient to an alternative drug	150 (41.3)	143 (43.2)	11 (36.7)	0.735
I order measurement of plasma level if side effects appear	115 (31.7)	111 (33.5)	9 (30.0)	0.836
I keep the same drug, but I change the brand (bioavailability issue)	45 (12.4)	29 (8.8)	5 (16.7)	0.181

Table 6 Quantitative Assessment of Some Attitudinal Statements Toward PK/TDM in Rank Order (Mean Values, Max Score 5)

Category	Consultant	GP	Resident	p-value
Pharmacokinetics and TDM will help me avoid drug toxicity	4.30	4.37	4.00	0.155
I believe pharmacokinetics and TDM are important to improve my practice	4.24	4.22	3.59	0.005*
I recommend that all physicians should apply pharmacokinetic principles when dealing with drug therapy, especially narrow therapeutic index drugs	4.24	4.26	3.44	0.243
Every hospital should have a therapeutic drug monitoring laboratory and facilities	4.24	4.27	4.00	0.545
Pharmacokinetics and TDM will help increase the efficacy of the prescribed medication	4.16	4.27	3.72	0.046*
I should use Pharmacokinetics and TDM to avoid subtherapeutic levels of the drug in the plasma.	4.15	4.13	3.59	0.012*
Pharmacokinetics and TDM will help in patient individualization (tailor doses for each patient)	4.13	4.16	3.72	0.113
I should consult with the clinical pharmacist about dosing or the change of medication	4.01	4.06	3.72	0.603
I should use Pharmacokinetics and TDM for prescribing the dose when I suspect ethnic differences in drug response	3.88	3.86	3.34	0.011*

Note: *Statistically significant (Kruskal–Wallis test).