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PROMs because it needs a physician’s global assessment [ 79 ] and (2) the Central
Sensitization Inventory (CSI) [ 80 ], because it is an index that combines various
assessment tools, but it is not a PROMs in essence.
None of the aforementioned questionnaires developed for FMS had a full and
proper validation process. This is partly due to the fact that many of the outcome
measures currently used in FMS were developed and validated for use in other
medical conditions, and were subsequently adopted for research and clinical prac-
tice. This aspect is not incorrect as it has facilitated basic exploration into the nature
and impact of FMS. It also represents a methodological advance over previous non-
standardized research. In addition, the validation of an instrument is a continuing
process. Testing validity is not established based on just a single approach, but after
a series of converging studies [ 81 ].
A summary of the psychometric properties of the PROMs will be discussed in
the next section. Table 7.2 presents a summary of the psychometric properties of the
main PROMs questionnaires developed for FMS patients.

Reliability

In general, internal consistency of the PROMs tools in FMS is good, with most of them
showing Cronbach’s α (alpha) > 0.8. The revised version of the FIQ shows the highest
internal consistency with α (alpha) = 0.95, followed by the PROMs-FM ( α [alpha] = 0.93)
and FFS ( α [alpha] = 0.92), although such high internal consistency may actually refl ect
overlapping of items or domains. The ICAF shows values from α (alpha) = 0.77–0.85,
and an overall α (alpha) = 0.85, and the original FIQ an α (alpha) = 0.82 for all items. The
FBI also has good consistency (Bladder Urgency and Pain α [alpha] = 0.76, Frequency
and Nocturia α [alpha] = 0.76, and ICSI/ICPS α [alpha] = 0.81). Internal consistency was
not available for VASFIQ, FSQ, or FHAQ.

Table 7.2 Summary of the main psychometric properties of the available FMS questionnaires

Aspect of validity

tested

Internal

consistency

Test–
retest Responsiveness
FIQ Construct +++ +++ +
FIQ-R Construct +++ ++ NT
FFS Face +++ ++ +
FBI Face ++ ++ NT
ICAF Construct +++ ++ +++
VASFIQ Construct NT NT NT
FSQ Face NT NT +
FHAQ NT NT NT NT
PROMs-FM Construct +++ +++ ++
Abbreviations : FIQ Fibromyalgia impact questionnaire, FIQ-R Revised version of the FIQ, ICAF
Combined Index of Fibromyalgia, FFS Fibrofatigue Scale, FBI Fibromyalgia Bladder Index,
VASFIQ FIQ in a visual analogue scale, FSQ Function and Symptom Questionnaire, FHAQ
Fibromyalgia Health Assessment Questionnaire, PROMs-FM Multi-Dimensional Patient Reported
Outcome Measures Questionnaire for Fibromyalgia, NT not tested, +++ high, ++ moderate, + poor

7 PROMs for Fibromyalgia