. 2019 Oct 5;15(1):26–39. doi: 10.1177/2049463719875164

Table 2.

Description of questionnaires used for data collection.

Symptom	Questionnaire	Purpose	Scoring	Reliability	Validity	Author
	Specific questionnaire/criteria
Diagnostic criteria for CFS/ME	American Centre for Disease Control and Prevention (CDC) diagnostic criteria for CFS/ME Symptom Inventory	Diagnostic criteria. See Table 1. In addition measures, frequency, intensity and duration of eight symptoms	No cut-off scores ⩾6 months of symptoms more than 4	Good Cronbachs alpha (α) ranging from 0.82–0.91 r ⩾ 0.77^17–19	Good Significant correlations r = 0.64–0.94(p < 0.001)^17,18	Fukuda et al.⁶ Wagner et al.¹⁷
Diagnostic criteria for FM	American College of Rheumatology Diagnostic Criteria for FM	Diagnostic criteria for FM. Figures 1 and 2 illustrate pain points	No cut-off score ⩾11 out of 18 tender points	N/A	N/A	Wolfe et al.⁷
Symptom experience of FM	The Fibromyalgia Impact Questionnaire (FIQ)	Comprises 20 items to assess the impact of symptoms of FM on patients’ daily lives and their response to any management/treatment offered. Questions address patient’s function, pain level, fatigue, sleep disturbance and psychological distress	Scores ⩾50 confirmed FM ⩾70 Severe FM	Good α = 0.72–0.93 r = 0.58–0.83^20,21	Good Significant correlations with the arthritis impact scale (p < 0.0001)²²	Burckhardt et al.²¹
	Generic questionnaire
Pain	McGill Pain Questionnaire (MPQ)	Measures frequency and intensity of pain, namely: affective, evaluative, sensory and miscellaneous. There is a body diagram to indicate areas of pain, 72 descriptor words to assess pain and a pain rating intensity scale. Each section is scored based on the guidelines	No cut-off score. Higher scores are indicative of an increased level of pain	Good α > 0.9 r ⩾ 0.89 (p ⩽ 0.001)^23,24	Good Coefficients ranging between 0.3 and 0.4²³	Melzack²³
Fatigue	Multidimensional Fatigue Inventory (MFI)	Measures 20 items on 5 dimensions: general, physical, mental, reduced motivation and reduced activity. Each dimension contains four items, two items relating to fatigue and two items which are contra-indicative of fatigue	Scores range from 4 to 20. Domains should not be summed together. High scores indicative of high levels of fatigue. A score of ⩾10 on the reduced activity subscale on the reduced activity subscale is indicative of fatigue, and severe fatigue is highlighted by a score of ⩾13 on the general fatigue scale	Good α > 0.80 with average of 0.84 Stability r ⩾ 0.72^25,26	Good p < 0.001 High scores 0.77 general fatigue, 0.7 physical fatigue, 0.61 reduced activity, 0.56 reduced motivation mental fatigue 0.23 (p < 0.01)^25,26	Smets et al.²⁵
Sleep quality	The Pittsburgh Sleep Quality Index (PSQI)	Measures sleep over the period of 1 month. Comprising 19 items generating seven component scores measuring; subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, the use of sleeping medication, and day-time dysfunction	Each scale scores 0 (no difficulty) to 3 (severe difficulty), which yields a score from 0 to 21. High scores indicate poor sleep quality and a global score of ⩾5 indicates sleep disturbance`	Good α > 0.83 Mean component scores r = 0.58 Individual items α > 0.83 r ⩾ 0.85 (p < 0.0001)^27–29	Good r = 0.33 (p < 0.001)^27,28	Buysse et al.²⁷
Quality of Life	The SF-36 V2 Questionnaire (SF-36 V2)	Comprises 36 questions within 8 domains of health namely: pain general health, vitality, physical functioning, social functioning, role limitations through physical problems, role limitations due to emotional problems and mental health including anxiety, depression, loss of behavioural/emotional control and physiological well being Results in two summary components of health physical and mental well-being of the patient. Aims to identify the positive and negative aspects of health which are most important to patients	Score on scale from 0 to 100, which represent the highest level of functioning. Poor HRQoL scores ⩽35, ⩾than 60 best HRQoL	Good α > 0.7 in all aspects except emotional role α > 0.6^30–32	Good Construct validity measuring >0.7³¹	Ware and Sherbourne³³
Anxiety and depression	Hospital Anxiety and Depression Scale (HADS)	Measure anxiety and depression in non-psychiatric populations Comprises 14 questions. Seven questions for anxiety (HADS-A) and seven questions for depression (HADS-D)	Each question scores 0 to 3. Total scores 0 to 42. No anxiety or depression ⩽ 7, mild 8 to 10, moderate 11 to 15 and severe ⩾ 16	Good α = 0.93–0.98, t = 0.93–0.97^34–36	Good Range = 0.6–0.8^34,35	Zigmond and Snaith³⁴
Ability to approach Illness	Multidimensional Health Locus of Control Form C (MHLOC Form C)	Measures self-related beliefs, comprised four scales namely: internal, chance, doctors and other people. Internal and chance scales comprise six questions; doctors and other people comprise three questions. A total of 18 questions	Measured on a 6-point Likert-type scale ranging from: 1 ‘strongly disagree’ to 6 ‘strongly agree’. Scores on the internal and chance subscales range from 6 to 36, with the doctors and other people subscales, scores ranging from 3 to 18, higher scores suggest stronger beliefs in that area. The minimum score is 3 and the maximum is 108	Good α = 0.60–0.75 Internal consistency measures = 0.71–0.87 t > 0.80^37,38	Good r = 0.38–0.65 (p < 0.001)^37,38	Wallston et al.³⁷ Michielsen et al.³⁸
Self-esteem	The Rosenberg Self-Esteem Scale (RSES)	Measures 10 items related to self-esteem. Includes feelings of self-worth and self-acceptance with 5 positive-worded questions and 5 negatively worded questions. The negative items have their scores reversed prior to the analysis	Each question measured on a 4-point scale. One total score. Results range from 0 to 30. Scores ⩽15 suggests low self-esteem	Good α = 0.78–0.89 t = 0.63–0.92 Internal consistence 0.77^39,40	Good r = 0.57–0.79 (p < 0.01)^41,40	Rosenberg⁴²

CFS/ME: Chronic Fatigue Syndrome/ Myalgic Encephalomyelitis; CDC: Centre for Disease Control and Prevention; FM: Fibromyalgia; FIQ: Fibromyalgia Impact Questionnaire; MPQ: McGill Pain Questionnaire; MFI: Multidimensional Fatigue Inventory; PSQI: Pittsburgh Sleep Quality Index; SF: short-form; HADS: Hospital Anxiety and Depression Scale; MHLOC: Multidimensional Health Locus of Control; RSES: Rosenberg Self-Esteem Scale.