Dating the "window of therapeutic opportunity" in early rheumatoid arthritis: accuracy of patient recall of arthritis symptom onset.

OBJECTIVE: A "window of therapeutic opportunity" has been hypothesized to be present in early rheumatoid arthritis (RA). To determine the date of this window, we must know the symptom-onset date of the RA. Patients participating in an observational study of early aggressive rheumatoid factor (RF) positive RA were evaluated to assess the accuracy of their recall of symptom-onset date by comparing the onset date they reported at the first visit with that reported on subsequent 6-monthly questionnaires.
METHODS: One hundred eighty-six patients with early RA (at entry: median disease duration 5.8 mo, mean RF 413.8 +/- 630.7 IU/ml, 20.6 +/- 10.9 swollen and 23.7 +/- 13.4 tender joints) completed a self-reported mailed questionnaire every 6 months for up to 5 years. As a part of each questionnaire, patients were asked to recall their RA symptom-onset date. These dates were then compared to the dates reported on the initial questionnaire.
RESULTS: Thirteen months after symptom onset (i.e., about 6 mo after study entry) 61% of patients recalled the symptom-onset date (within 1 mo) that they had reported at baseline; the proportion decreased to 39% at 31 months and 25% after 70 months. During this period, the proportion overestimating RA duration remained about 20%, but the proportion underestimating it increased from 23% at 13 months to 39% at 31 months, and to 50% after 56 months. Patients with longer disease duration, less disease activity, and higher pain levels tended to be less accurate.
CONCLUSION: Accuracy of recall of RA symptom-onset date by patients tends to decline over a period of 5 years. This should be taken into consideration when enrolling patients, when interpreting the findings of early RA clinical trials, and when attempting to ascertain the presence of a window of therapeutic opportunity.