The ICAF is a self-administered questionnaire designed for the evaluation of multidimensional aspects of FM patients . As previously mentioned, it already contains a severity reference by assigning the corresponding place in the original distribution of patients studied for the development of the instrument. This explains the normalized punctuations (T score) used in this questionnaire. Also in the development of the ICAF, external criteria such as labor status, presence of trigger points and six-minute walk test were employed for the validation of the punctuation distribution .
In the current work, an additional criterion has been considered: measuring global severity by the number of consumed drugs since it better reflects the overall situation of the patient compared with the severity based on pain intensity.
It is known that in addition to generalized pain in FM there exist other relevant clinical manifestations such as sleep disorders, fatigue, depression, or anxiety. For this reason, it is very common that patients with FM consume other drugs acting over NS for treating all those clinical manifestations, in addition to analgesics and NSAID to alleviate pain.
In this work, we have started with the hypothesis that the higher the severity of the disease, the higher number of drugs consumed by the patient. This fact has been previously confirmed by Sánchez et al.  who demonstrated that economical costs associated with drug treatment in FM increase by comorbidity rather than with drugs to alleviate pain. We have considered that our point of view may be questionable, but we also believe that this approach may help clarify the always difficult aspect of quantifying severity in FM patients.
In our cohort of patients, distribution of severity after applying ICAF calculated cutoff points was 14, 35 and 50 % for mild, moderate and severe forms, respectively, whereas distribution of the severity following the FIQ cutoff points yielded 3, 18 and 79 %, respectively. As it can be seen, the distribution is more normal using the ICAF cutoff points with a lesser number of severe forms and a higher frequency of mild ones. In the original work by Bennett et al.  where cutoff points were established for the FIQ, the mild forms were only observed in 6 % of the patients.
Our results confirm the initial working hypothesis and the calculated cutoff points allow the classification of patients in a more practical way than other existing questionnaires. Classification of the disease in terms of severity also allows to establish an overall prognosis. In this work, 77 % of patients classified as mild still remained with the same degree of severity, whereas 50 % still continued to be classified as severe 1 year later.
To classify patients by severity also has several implications in the field of therapeutic decisions and economic costs of resource utilization. For those patients classified as severe, it seems logical to intensify treatment specially by using other therapeutic approaches such as physical exercise programs as well as psychological therapeutic modalities. Incorporating psychoeducational resources in primary care may improve therapeutic response and reduce the probability of impairment in these patients .
The ICAF questionnaire also provides interesting information through the different factors in which it is composed. The emotional factor provides the most factorial component with respect to the total score and patients with higher punctuation in the emotional factor also have a higher total score, as it is shown in this work. However, these patients also have a good response to the treatment and they would be the better candidates for drug treatment, especially antidepressants.
A high punctuation in the physical factor is associated with a long-term poorer response, as it is shown in our results. In this group are included those patients with higher degrees of fatigue, closer to chronic fatigue syndrome, and it is known that these patients have a poor response to pharmacological treatments, especially to antidepressants . In this group of patients, exercise programs should be emphasized and more sophisticated physiotherapy programs with well-elaborated adherence strategies may be the best therapeutic approach.
Although both coping factors only add a small percentage to the ICAF total score, the evaluation of coping strategies is very useful . Indeed, as shown by our results, coping factor scores are determinant to determine the severity of the disease. Patients with high passive coping scores have higher total scores, consume more drugs and also have a poorer prognostic. Intensifying drug therapy in these patients does not seem to be the best strategy since they are already taking more drugs than the rest of the patients and that does not work properly for them. They need a personalized psychotherapeutic intervention or a guided psychological therapy to improve coping with the disease and to reduce the probability of impairment. Alternatively, psychological group therapy or via the Internet has been also shown to be useful [12, 13].
In comparison with other FM global outcome indexes, the ICAF shows some strengths and some disadvantages. As a clear strength, it is remarkable that the ICAF has been confronted with external criteria not coming from the patient self-report, in contrast with other tools and questionnaires such as CODI , CRSFS  or FiRST , in which no external criteria were used for its construction. Another strength is the presence of the two coping factors, because good coping strategies are very important in the favorable outcome in chronic diseases, and the aforementioned questionnaires do not specifically consider such aspects.
It is difficult to cover all principal clinical aspects of FM with a short questionnaire. Indeed, the ICAF contains 59 items, while CODI has 26 , CRSFS has 20  and FiRST has 6 items . Even considering that shortness is an important aspect of a questionnaire, it could not be at the expense of eliminating basic aspects in the evaluation of an FM patient, as it occurs with emotional aspects in the FiRST questionnaire . On the other hand, a more complete questionnaire may contribute to clarify some believes that general practitioners have about FM .
Outcomes measures in FM still remain controversial. Recently, the OMERACT has elaborated a report based on experts’ opinion about the most important outcome measures that must be evaluated in patients with FM . However, an online interview with patients  shows that there exist some highly valued variables by the patients that are not included in the experts inform of OMERACT. A possible explanation of this divergence between patients and experts may be that for some aspects such as stiffness or cognitive dysfunction, highly evaluated by the patients, there are no effective instruments of measurement, and for this reason, the experts do not include them.
In recent clinical trials with drugs for treating FM, the most common outcome measure is pain . However, pain is just an aspect of the disease and in some patients not even the most important clinical manifestation. When a clinical trial is designed, if this consideration is not taken into account, there may be different populations of FM patients with different responses to the same treatment. So, a favorable response in the outcome of pain may be misinterpreted if the intervention does not improve some of the aspects of FM.
The strong point of this study is that results about classification of severity obtained in a multicentric cohort of patients with FM have been well reproduced in a different cohort of patients in daily clinical practice showing the same useful information.
The principal limitation of this study lies in that the ICAF has not been proven in clinical trials and has not been compared with other tools. However, if ICAF has shown to be sensible to the changes that occur in daily practice conditions—both in short and in longer periods of time—the response will probably be similar under clinical trial conditions.
In addition, in this study, we have not established a comparison with an untreated control group, and for this reason, it is not possible to determine whether changes observed throughout time are due to the treatment itself.
In conclusion, the ICAF has shown to be an excellent outcome measure, which allows the classification of FM patients by severity in a very practical way, to determine the prognostic of the disease and to predict the response to the treatment through its different component factors. These are all important issues which impact positively on usual clinical practice with FM patients, and provide invaluable information which is now difficult and time consuming to obtain.