Journal of IiME Volume 4 Issue 1 www.investinme.org Definition of Recovery in Chronic Fatigue Syndrome (continued) Results The first question of the MOS-36 is a general rating of health status. All ten subjects in this study rated themselves as either "good" or "very good," confirming the perception that they viewed themselves as either "recovered" or "almost recovered". No subject, other than control subjects, rated themselves as "excellent." Patients who were "recovered" were quite different from healthy controls in three areas: VAS, Ability Scale and FIS. For the Visual Analog Scale, mean recovered CFS score was 19.8 +/- 14.67 while the mean control subject score was 6.1 +/- 4.63. This mean difference is significant at the 0.05 alpha level (p=0.011). For the FIS, mean recovered score was 22.8 +/- 25.83, and the mean control score was 4 +/5.81. This difference is significant with a p-value of 0.038. Mean scores for the Bell Ability scale were 99 +/- 3.16 for recovered and 90 +/-12.47 for controls. This was significant with a p value of 0.040. Scores for the MOS-36 will be presented under separate cover. However, the two groups did not differ in the hours of activity scale. Recovered CFS subjects had a mean of 14 +/- 1.94 hours of upright activity, while control subjects had 15.5 hrs +/-1.67 hours of upright activity. The average difference of the means proved to be not statistically significant (p=0.080). The data is presented in Table 1. Discussion The results of this small study suggest that all of ten persons who, in clinical follow-up had stated they had either "recovered" or "almost recovered" had persistent symptoms on several questionnaires. In fact, if the MOS-36 scores are used as an index of disability as suggested by the CDC empirical case definition(8), five of the ten "recovered" subjects would still meet criteria as having CFS. Comparing the ten "recovered" subjects to the healthy controls, clear differences were seen in visual analog scores, Bell Ability Scale, and the Fatigue Impact Scale scores. Of these three, the least significant scores were seen in the Ability scale, perhaps because this scale attempts to combine orthostatic intolerance with somatic symptoms. However, the Hours of Activity Scale scores, a measure of orthostatic intolerance, were the same in the two groups. This implies is that the perception of recovery is based on the symptom of orthostatic intolerance and is independent of somatic symptoms. That is, when persons with CFS improve and reach a point where they can sustain upright Invest in ME (Charity Nr. 1114035) activity for more than twelve hours in a day, they perceive themselves as "recovered" or "almost recovered", despite the fact that other somatic symptoms remain. This observation has relevance in the definition of recovery in ME/CFS, an illness that has no clearly defined biologic markers at present. If confirmed in larger studies, it may explain the large discrepancy in recovery rates in studies of ME/CFS. Thus, future studies of the natural history of the illness will need to discriminate between somatic symptoms and overall activity. It may be that after a number of years, persons with ME/CFS adjust to ongoing somatic symptoms. And if they return to normal activities with improvement of orthostatic intolerance, they perceive themselves as "recovered", when in fact only one aspect of their illness has improved. Again, if this is confirmed, it implies that full recovery from ME/CFS is exceedingly rare. One specific concern related to the definition of recovery in ME/CFS is that when people consider themselves recovered, they feel able to donate blood. One "recovered" subject in this study had normal activity but significant somatic symptoms and was a regular blood donor. Recently the gammaretrovirus XMRV has been implicated in persons with CFS(15). While the relationship of XMRV and ME/CFS is still under debate, these findings carry important implications. Furthermore, it should be remembered that only 20% of persons with ME/CFS receive a diagnosis of CFS from their health care provider (16). A further possible implication of the uncertain definition of recovery in ME/CFS is the interpretation of XMRV incidence in the healthy control population. It will be important in the future to inquire if subjects have ever had a CFS-like illness in the past. References 1. Bell D, Bell K. Ann Intern Med. 1988;109:[Letter]167. 2. Holmes G, Kaplan J, Gantz N, al e. Chronic fatigue syndrome: a working case definition. Ann Intern Med. 1988;108:387-9. 3. Parish J. Epidemic neuromyasthenia: a reapprailsal. Journal of International Research Communications Medical Science. 1974;2:22-6. 4. Bell D. Children with ME/CFIDS: Overview and review of the literature. Ottawa: Nightingale Research Foundation; 1992. 5. Bell D, Bell K. Chronic fatigue syndrome in Page 25/56

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