The relationship between change in subjective outcome and change in disease: a potential paradox.
BACKGROUND
Response shift theory suggests that improvements in health lead patients to change their internal standards and re-assess former health states as worse than initially rated when using retrospective ratings via the then-test. The predictions of response shift theory can be illustrated using prospect theory, whereby a change in current health causes a change in reference frame. Therefore, if health deteriorates, the former health state will receive a better rating, whereas if it improves, the former health state will receive a worse rating.


OBJECTIVE
To explore the predictions of response shift and prospect theory by relating subjective change to objective change.


METHODS
Baseline and 3-month follow-up data from a cohort of rheumatoid arthritis patients (N = 197) starting on TNFalpha-blocking agents were used. Objective disease change was classified according to a disease-specific clinical outcome measure (DAS28). Visual analogue scales (VAS) for general health (GH) and pain were used as self-reported measures. Three months after starting on anti-TNFalpha, patients used the then-test to re-rate their baseline health with regard to general health and pain. Differences between then-test value and baseline values were calculated and tested between improved, non-improved and deteriorated patients by the Student t-test.


RESULTS
At 3 months, 51 (25.9%) patients had good improvement in health, 83 (42.1%) had moderate improvement, and 63 (32.0%) had no improvement or deteriorated in health. All patients no matter whether they improved, did not improve, or even became worse rated their health as worse retrospectively. The difference between the then-test rating and the baseline value was similarly sized in all groups.


CONCLUSIONS
More positive ratings of retrospective health are independent of disease change. This suggests that patients do not necessarily change their standards in line with their disease change, and therefore it is inappropriate to use the then-test to correct for such a change. If a then-test is used to correct for shifts in internal standards, it might lead to the paradoxical result that patients who do not improve or even deteriorate increase significantly on self-reported health and pain. An alternative explanation for differences in retrospective and prospective ratings of health is the implicit theory of change which is more successful in explaining our results than prospect theory.
Kievit
Wietske
W
Department of Rheumatology, Radboud University Nijmegen Medical Centre, PO box 9101, 6500 HB, Nijmegen, The Netherlands. w.kievit@reuma.umcn.nl
Hendrikx
Jos
J
Stalmeier
Peep F M
PF
van de Laar
Mart A F J
MA
Van Riel
Piet L C M
PL
Adang
Eddy M
EM
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000188:drug therapy / Q000523:psychology*; D001294:Attitude to Health; D001685:Biological Factors / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors
D001685:Biological Factors; D014409:Tumor Necrosis Factor-alpha
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