A decrease in disease activity score (DAS) level is associated with a decrease in health assessment questionnaire (HAQ) score, independent of follow-up duration, during 5 years of tightly controlled treatment: results from the BeSt study.
OBJECTIVE
To assess the relationship between a decrease in disease activity score (DAS) and functional ability during 5 years of DAS-steered treatment in recent-onset rheumatoid arthritis (RA) patients, taking into account absolute DAS levels and follow-up duration.


METHODS
Data from the BeSt study were used, in which treatment was aimed at achieving DAS ≤2.4. The longitudinal relationship between 3-monthly measured DAS and health assessment questionnaire (HAQ) score was assessed using linear mixed modelling during 5 years of treatment, with DAS and HAQ 3 months earlier, change in DAS in last 3 months (delta DAS), time (log-transformed) and their interactions as determinants.


RESULTS
Predictors for HAQ were: previous DAS, delta DAS, ln time, the interaction previous DAS×delta DAS, and previous HAQ. The interaction ln time×delta DAS was non-significant, indicating that the association between delta DAS and HAQ was independent of follow-up duration. A decrease from a higher DAS was associated with a smaller HAQ decrease than for a similar decrease from a lower DAS, indicating a non-linear relationship between DAS and HAQ.


CONCLUSIONS
At any time during 5 years of follow-up, a decrease in DAS was associated with a better functional ability. The magnitude of HAQ improvement depends on the DAS decrease and on the absolute DAS level.
Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
E
E
van der Kooi
N B
NB
Klarenbeek
M
M
Güler-Yüksel
P J S M
PJ
Kerstens
P A H M
PA
van der Lubbe
M L
ML
Westedt
S
S
ten Wolde
T W J
TW
Huizinga
B A C
BA
Dijkmans
C F
CF
Allaart
D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000503:physiopathology; D004334:Drug Administration Schedule; D004812:Epidemiologic Methods; D006801:Humans; D012720:Severity of Illness Index; D016896:Treatment Outcome
D018501:Antirheumatic Agents