Session Information
Title: Systemic Lupus Erythematosus - Clinical Aspects: Non-biologic Disease-modifying Antirheumatic Drugs
Session Type: Abstract Submissions (ACR)
Background/Purpose: Hydroxychloroquine is used for both its effect on SLE disease activity (cutaneous and arthritis) and for its preventive roles (reduction in flares, renal damage, thrombosis). HCQ blood levels have been predominantly used to identify nonadherence; to date, they have not correlated well with disease activity.
Methods:
357 SLE patients (mean age 44.7, 94% female, 45% Caucasian, 45% African-American, and 10% other ethnicity) had hydroxychloroquine blood levels measured (therapeutic 500-1500 ng/mL in whole blood) and same day assessment of global disease activity by Physician Global Assessment (PGA, 0 to 3 VAS) and SELENA-SLEDAI.
Results:
53 (15%) had 0 level, meaning complete nonadherence. 110 (31%) had levels between 15-500 ng/mL indicating partial adherence. 167 (47%) had therapeutic levels. Surprisingly, 27.8% had supratherapeutic levels. This supratherapeutic group was appropriately dosed for weight, age, and renal function.
Table 1. Effect of Hydroxychloroquine level on Clinical Characteristics (as categorical variables)
|
Demographic Characteristics |
HCQ <15 (N=53) |
HCQ (15-500) (N=110) |
HCQ (500-1500) (N=167) |
HCQ ≥1500 (N=27) |
Adjusted P-Value§ |
Adjusted P-value for therapeutic (≥500) vs non-therapeutic levels§ |
|
|
n (%) |
n (%) |
n (%) |
n (%) |
|
|
|
Gender Female |
52 (98) |
106 (96) |
150 (90) |
26 (96) |
0.059 |
0.016 |
|
Male |
1 (2) |
4 (4) |
17 (10) |
1 (4) |
|
|
|
Ethnicity Caucasian |
24 (45) |
49 (45) |
77 (46) |
12 (44) |
0.96 |
0.70 |
|
African-American |
27 (51) |
49 (45) |
70 (42) |
13 (48) |
|
|
|
Other |
2 (4) |
12 (11) |
20 (12) |
2 (7) |
|
|
|
Age at baseline ≤30 years |
6 (11) |
16 (15) |
29 (17) |
6 (22) |
0.63 |
0.29 |
|
>30 years |
47 (89) |
94 (85) |
138 (83) |
21 (78) |
|
|
|
Education ≤12 years |
22 (42) |
41 (38) |
56 (34) |
12 (44) |
0.74 |
0.55 |
|
>12 years |
30 (58) |
66 (62) |
108 (66) |
15 (56) |
|
|
|
Family income ≤$50,000 |
32 (62) |
60 (56) |
82 (50) |
17 (63) |
0.60 |
0.37 |
|
>$50,000 |
20 (38) |
47 (44) |
81 (50) |
10 (37) |
|
|
|
PGA>1 |
7 (15) |
21 (22) |
28 (18) |
8 (33) |
0.23 |
0.86 |
|
SELENA-SLEDAI>2 |
16 (30) |
35 (32) |
49 (29) |
9 (33) |
0.98 |
0.86 |
|
Prednisone >0 |
25 (56) |
31 (33) |
56 (36) |
15 (63) |
0.0051 |
0.90 |
|
Low C3 |
9 (17) |
19 (18) |
36 (22) |
2 (7) |
0.27 |
0.80 |
|
Low C4 |
7 (13) |
16 (15) |
17 (10) |
1 (4) |
0.25 |
0.11 |
|
BMI>30 |
15 (28) |
38 (35) |
51 (31) |
6 (22) |
0.52 |
0.72 |
|
Anti-dsDNA |
10 (19) |
19 (18) |
36 (22) |
5 (19) |
0.88 |
0.64 |
|
Creatinine>1.4 mg/dl |
4 (8) |
10 (9) |
13 (8) |
4 (15) |
0.56 |
0.83 |
|
|
Mean (SD) |
Mean (SD) |
Mean (SD) |
Mean (SD) |
|
|
|
PGA |
0.7 (0.7) |
0.7 (0.7) |
0.6 (0.6) |
0.9 (0.9) |
0.24 |
0.50 |
|
SELENA-SLEDAI |
2.5 (3.5) |
2.4 (3.1) |
2.2 (2.6) |
1.9 (2.4) |
0.051 |
0.64 |
|
Prednisone dose (mg/d) |
3.1 (3.5) |
3.1 (8.0) |
2.6 (6.1) |
7.8 (11.5) |
0.0029 |
0.76 |
§Comparison between among different HCQ groups; adjusted for age, ethnicity, and gender.
Conclusion: Hydroxychloroquine blood levels remain important in assessing adherence, but they are disappointing in not being correlated with current disease activity (by PGA or SLEDAI). In fact, the identification of the “supratherapeutic” group explains this paradox, as they had greater PGA, SLEDAI, and prednisone use. Several hypotheses (patients increasing HCQ dose on their own for disease activity vs genetic differences in metabolism of HCQ) could explain a “supratherapeutic” group. Our data also indicate that nonadherence should be subdivided into two groups: complete nonadherence (15%) and partial nonadherence (31%), as the clinical implications are quite different.
Disclosure:
M. Petri,
None;
H. Fang,
None;
W. Clarke,
None.
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