Of the 280 patients included, one was unable to perform several neuropsychological tests due to visual impairment unrelated to Lyme disease. Of the 279 patients fully examined, 239 (85.4%) displayed sufficient performance validity.
Table 1 shows patient characteristics stratified by performance validity status.
Table 1. Demographic and psychosocial factors stratified by performance validitya
Characteristic
|
Good performance validity
(n=239)
|
Poor performance validity
(n=40)
|
P Value
|
Women, no. (%)
|
109 (45.6)
|
19 (47.5)
|
0.82
|
Education level, no. (%)
|
|
|
0.03
|
Low (≤8 years)
|
1 (0.4)
|
0 (0)
|
Average (9-11 years)
|
125 (52.7)
|
28 (71.8)
|
High (≥12 years)
|
111 (46.8)
|
11 (28.2)
|
Paid work, no. (%)
|
154 (64.7)
|
17 (43.6)
|
0.01
|
Age, mean (± SD), years
|
48.7 (11.9)
|
49.0 (11.9)
|
0.87
|
Duration of symptoms, median (IQR), years
|
2.7 (1.3 – 6.3)
|
1.8 (0.7 – 5.7)
|
0.13
|
Previous antibiotic treatment for Lyme disease, no. (%)
|
213 (89,1)
|
33 (82.5)
|
0.23
|
Delay symptom onset and treatment, median (IQR), weeks
|
22.5 (3.0 – 103.5)
|
15.5 (2.0 – 69.0)
|
0.41
|
History of meningoradiculitis, no. (%)c (neuroborreliosis)
|
18 (7.5)
|
3 (7.7)
|
0.97
|
CFQ, mean (95% CI)
|
|
|
|
Orientation
|
3.92 (3.65 - 4.18)
|
4.98 (4.20 - 5.75)
|
0.004b
|
Distractibility
|
11.29 (10.71 - 11.87)
|
12.98 (11.58 - 14.37)
|
0.03
|
Blunders
|
7.04 (6.70 - 7.38)
|
7.95 (7.15 - 8.75)
|
0.05
|
Memory
|
7.32 (7.05 - 7.59)
|
7.03 (6.28 - 7.77)
|
0.43
|
Total
|
43.23 (41.52 - 44.94)
|
47.73 (43.24 - 52.21)
|
0.05
|
HADS, mean (95% CI)
|
|
|
|
Anxiety
|
6.36 (5.82 - 6.90)
|
6.08 (4.90 - 7.26)
|
0.71
|
Depression
|
7.47 (6.98 - 7.96)
|
8.76 (7.33 - 10.19)
|
0.06
|
CIS, mean (95% CI)
|
|
|
|
Fatigue severity
|
43.62 (42.33 - 44.91)
|
47.25 (44.38 - 50.11)
|
0.03
|
Concentration
|
23.84 (22.92 - 24.76)
|
25.35 (22.74 - 27.96)
|
0.23
|
Motivation
|
16.67 (15.92 - 17.42)
|
17.93 (15.93 - 19.92)
|
0.22
|
Activity
|
13.92 (13.27 - 14.57)
|
16.15 (14.73 - 17.57)
|
0.01b
|
Total
|
98.03 (95.34 - 100.72)
|
106.65 (100.82 - 112.49)
|
0.02
|
Self-efficacy, mean (95% CI)
|
17.28 (16.60 - 17.96)
|
15.62 (13.92 - 17.31)
|
0.07
|
ICQ, mean (95% CI)
|
|
|
|
Helplessness
|
13.26 (12.71 - 13.80)
|
15.54 (14.20 - 16.87)
|
0.002b
|
Acceptance
|
13.68 (13.17 - 14.20)
|
13.42 (12.27 - 14.58)
|
0.70
|
Perceived benefits
|
11.35 (10.82 - 11.88)
|
12.63 (11.43 - 13.82)
|
0.07
|
EPQ, mean (95% CI)
|
|
|
|
Neuroticism
|
8.27 (7.59 - 8.96)
|
7.67 (6.22 - 9.12)
|
0.50
|
Extraversion
|
11.44 (10.83 - 12.04)
|
12.21 (10.60 - 13.81)
|
0.34
|
PSWQ, mean (95% CI)
|
42.17 (40.55 - 43.78)
|
42.15 (38.30 - 46.00)
|
0.99
|
BSQ, mean (95% CI)
|
2.27 (2.19 - 2.35)
|
2.38 (2.17 - 2.59)
|
0.33
|
Abbreviations: BSQ, Body Sensations Questionnaire; CFQ, Dutch version of the Cognitive Failures Questionnaire; CIS, Checklist Individual Strength; EPQ, Eysenck Personality Questionnaire; HADS, Hospital Anxiety and Depression Scale; ICQ, Illness Cognition Questionnaire; PSWQ, Penn-State Worry Questionnaire
a Between-group differences in characteristics were analyzed with analysis of variance for continuous variables, chi-square tests for proportions, and Kruskal-Wallis tests for ordinal variables and data that were not normally distributed.
b Significant with the Benjamini-Hochberg correction, accepting a false discovery rate of 0.10.
c Diagnosis by intrathecal Borrelia antibody production.
Patients with insufficient performance validity had significantly lower education levels and less often paid work. They also reported significantly more feelings of helplessness (ICQ subscale helplessness, F(1,275)=9.77), experienced more physical fatigue (CIS Activity subscale, F(1,276)=6.79), and reported more problems in daily orientation (CFQ Orientation subscale, F(1,276)=8.40).
Compared to the normative sample, 2.9% of patients (7/239) were cognitively impaired. For the separate domains, 2.1% were impaired on episodic memory (5/239), 5.4% on working memory/ attention (13/239), 0.8% on verbal fluency (2/239), 2.1% on information-processing speed (5/239), and 0.4% on executive function (1/239). Table 2 shows the raw neuropsychological test scores as well as mean z-scores, and percentage of individuals with a cognitive decrement (z-score <1.0 SD below the age, sex and education-adjusted normative mean).
Table 2. Neuropsychological test scores per domain and per testa
|
Good performance validity
(n=239)
|
Poor performance validity
(n=40)
|
mean raw score (SD)
|
mean z-score (SD)
|
cognitive decrement
no. (%)
|
mean raw score (SD)
|
mean z-score (SD)
|
cognitive decrement
no. (%)
|
Episodic memory
|
-0.12 (0.71)
|
-0.40 (0.81)
|
RAVLT (immediate recall,
total of trials 1-5)
|
45.3 (8.4)
|
-0.12 (0.71)
|
29 (12.1)
|
41.0 (8.5)
|
-0.43 (0.75)
|
8 (20.0)
|
RAVLT (delayed recall)
|
9.4 (2.8)
|
-0.11 (0.80)
|
30 (12.6)
|
8.4 (3.3)
|
-0.37 (1.01)
|
9 (22.5)
|
Working memory/attention
|
0.11 (1.01)
|
-0.40 (0.86)
|
Digit Span
|
15.4 (3.3)
|
0.11 (1.01)
|
31 (13.0)
|
13.5 (2.7)
|
-0.40 (0.86)
|
10 (25.0)
|
Language
|
0.02 (0.74)
|
-0.04 (0.84)
|
Category Fluency (animals)
|
25.4 (5.8)
|
-0.03 (0.79)
|
25 (10.5)
|
24.3 (6.5)
|
-0.11 (0.96)
|
8 (20.0)
|
Category Fluency (professions)
|
19.1 (4.8)
|
0.07 (0.91)
|
28 (11.7)
|
18.2 (4.3)
|
0.03 (0.94)
|
6 (15.0)
|
Information-processing speed
|
0.02 (0.72)
|
-0.49 (0.93)
|
Trail Making Test part Ab
|
30.5 (11.5)
|
0.19 (0.84)
|
24 (10.0)
|
33.9 (12.0)
|
-0.01 (0.85)
|
6 (15.4)
|
Stroop Color-Word Test (Card I)b
|
44.1 (8.7)
|
-0.10 (0.99)
|
46 (19.3)
|
48.0 (9.9)
|
-0.50 (1.13)
|
8 (21.1)
|
Stroop Color-Word Test (Card II)b
|
58.9 (12.5)
|
-0.23 (1.10)
|
53 (22.3)
|
66.1 (13.9)
|
-0.84 (1.18)
|
16 (42.1)
|
Symbol-Digit Substitution Test
|
57.6 (11.3)
|
0.05 (0.99)
|
31 (13.0)
|
49.5 (10.6)
|
-0.59 (1.10)
|
11 (27.5)
|
Executive functions
|
0.33 (0.68)
|
0.11 (0.73)
|
Trail Making Test interference
score (Part B/Part A)b
|
2.3 (0.7)
|
-0.13 (0.99)
|
45 (18.8)
|
2.5 (0.6)
|
-0.38 (0.92)
|
9 (23.1)
|
Stroop interference score
(Card III/average Card I and II)b
|
1.8 (0.3)
|
0.78 (0.71)
|
4 (1.7)
|
1.9 (0.3)
|
0.61 (0.86)
|
1 (2.6)
|
Abbreviations: RAVLT = Rey Auditory Verbal Learning Test
a mean standardized age, sex and education-adjusted normative z-scores(SD) are presented for the domains, mean raw scores(SD), as well as mean z-scores(SD), and percentage of subjects with a cognitive decrement (z-score <1.0 SD below the age, sex and education-adjusted normative mean) are presented for the separate tests. Higher scores represent better cognitive performance, unless otherwise indicated.
b higher scores represent worse cognitive performance
No significant correlation between overall cognitive performance and subjective cognitive complaints (CFQ total score) was found in patients with sufficient performance validity (r=0.120, p=0.064). A significant correlation was found between objective performance and problems in orientation (CFQ subscale orientation; r=0.246 (p<0.001). Performance and other CFQ subscales did not show any correlations (p=0.10-0.98).