Redundant laboratory testing on referral from general practice to the outpatient clinic: a post-hoc analysis

Bram EL Vrijsen; Maarten J ten Berg; Wouter W van Solinge; Jan Westerink

doi:10.3399/BJGPO.2021.0134

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Table 1. Baseline characteristics

Characteristic	Pre-visit testing	Post-visit testing
Total, n	104	191
Age, years (95% CI)	53.4 (49.7 to 57.1)	52.3 (49.6 to 54.9)
Female, n (%)	66 (63)	129 (68)
Referral reason, n (%)^a
Abdominal complaints	12 (12)	23 (12)
Abnormal laboratory test	16 (15)	28 (15)
Anaemia	12 (12)	28 (15)
Fatigue	37 (36)	47 (25)
Lymphadenopathy/suspected malignancy	1 (1)	8 (4)
Weight loss	15 (14)	29 (15)
Other	24 (23)	43 (23)

^aCategories are not exclusive.

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Table 2. Number of repeats of primary care physician’s tests depending on laboratory testing strategy in the outpatient clinic

Tests, normal results, and repeat tests, median (IQR)	Pre-visittesting (n = 104)	Post-visittesting (n = 191)	P value
Tests	12.5 (8.8–17.0)	14.0 (10.0–18.0)	—
Normal results	9.5 (6.0–14.0)	11.0 (8.0–14.0)	—
Repeats overall	9.5 (6.0–13.0)	8.0 (4.0–11.0)	P<0.001^a
Repeats of normal results	8.0 (3.8–10.0)	5.0 (3.0–9.0)	P<0.001^a

^aStatistically tested using the Wilcoxon rank-sum test. IQR = interquartile range.

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Table 3. Ten most commonly ordered tests with repetition rates and rates of normal tests remaining normal on retesting

Test	Tests by primary care physician, n	Repeats, n (%)	Normal results on first test being repeated, n (%)	Normal repeats remaining normal, n (%)
Haemoglobin	247	217 (88)	141 (84)	134 (95)
MCV	237	204 (86)	170 (85)	163 (96)
Leucocytes	227	198 (87)	154 (85)	136 (88)
Creatinine	213	185 (87)	152 (85)	147 (97)
ESR	198	151 (76)	96 (77)	95 (99)
TSH	192	141 (73)	129 (75)	125 (97)
Glucose	191	114 (60)	73 (57)	57 (78)
Thrombocytes	188	162 (86)	142 (85)	136 (96)
ALT	164	136 (83)	111 (80)	103 (93)
Leucocyte differential	156	114 (73)	106 (72)	82 (77)

ALT = alanine transaminase. ESR = erythrocyte sedimentation rate. MCV = mean corpuscular volume. TSH = thyroid stimulating hormone.

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Table 4. Tests with the highest rates of normal test results becoming abnormal on retesting

Test	Normal results being repeated, n (% of normal results)	Normal repeats remaining normal, n (% of normal repeats)
Urine screening	14 (82)	4 (29)
Creatine kinase	2 (22)	1 (50)
Iron	3 (14)	2 (67)
Cholesterol	4 (6)	3 (75)
Reticulocytes	8 (29)	6 (75)
Leucocyte differential	106 (72)	82 (77)
Potassium	90 (74)	70 (78)
Glucose	73 (57)	57 (78)
Sodium	83 (75)	67 (81)
Ferritin	11 (31)	9 (82)

Supplementary Data

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Test: Supplementary material is not copyedited or typeset, and is published as supplied by the author(s). The author(s) retain(s) responsibility for its accuracy.

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