Table 1 Summary of measurement properties of tools for measuring the quality of life used in the identified studies

CFQ-R 14+

9 [23–31]

Internal consistency: α = 0.18 (treatment burden)– 0.94 (physical functioning) [23]; α = 0.54 (social functioning)– 0.95 (physical functioning) [24]; α = 0.29 (social functioning)– 0.86 (respiratory symptoms) [26]; α = 0.31 (digestive symptoms)– 0.96 (physical functioning) [27]; α = 0.51 (treatment burden)– 0.94 (physical functioning) [28]; α = 0.53 (social functioning)– 0.93 (physical functioning) [29]; α = 0.47 (social functioning)– 0.90 (physical functioning) [31].

Reliability– test-retest: ICC = 0.45 (social functioning/ treatment burden)– 0.90 (respiratory symptoms) [23]; ICC = -0.19 (social functioning)– 0.99 (physical functioning) [25]; ICC = 0.47 (digestive symptoms)– 0.95 (physical functioning) [27]; ICC = 0.71 (treatment burden)– 0.96 (physical functioning) [29].

Construct validity (comparison between other instruments): the tool had satisfactory results of convergent validity with SF-36 [23] and SGRQ [27].

Construct validity (comparison between subgroups): CFQ-R 14 + discriminate between different levels of disease severity (determined by FEV₁%) [23, 24, 27,28,29].

CFQ 14+

3 [32–34]

Structural validity: nine domains relating to HRQoL, 3 symptom scales and 1 health perception scale were separated [32, 34].

Internal consistency: α = 0.66 (body image)– 0.93 (physical functioning) [32]; α = 0.45 (body image)– 0.92 (physical functioning) [33]; α = 0.71 (eating disturbances)– 0.94 (physical functioning) [34].

Reliability– test-retest: ICC = 0.72 (energy)– 0.97 (role limitations, perception of health) [32]; ICC = 0.72 (digestive symptoms)– 0.98 (physical functioning, role limitations) [33].

Construct validity (comparison between other instruments): the tool had satisfactory results of convergent validity with NHP [32].

Construct validity (comparison between subgroups): CFQ 14 + does not discriminate between different levels of disease severity (determined by FEV₁%) in the case of several domains (energy, emotional state, role limitations, embarrassment and digestive symptoms) [33, 34].

Responsiveness (comparison before and after rehabilitation): difference was observed between the results before and after rehabilitation in terms of physical functioning, energy, emotional state, body image, respiratory symptoms and weight problem [34].

Responsiveness (comparison before and after antibiotic treatment for exacerbation): results of 4 domains changed before and after antibiotic therapy for exacerbation (physical functioning (ES = 0.38), energy (ES = 0.68), emotions (ES = 0.26), and respiratory symptoms (ES = 0.63)) [32].

CFQ-R-8D

1 [35]

Structural validity: eight domains were separated (physical functioning, vitality, emotional functioning, role functioning, respiratory symptoms, body image, digestive symptoms, and treatment burden).

CFQoL

5 [36–40]

Structural validity: nine domains were separated: physical functioning, social functioning, treatment issues, chest symptoms, emotional functioning, concerns for the future, interpersonal relationships, body image, and career concerns [36, 38].

Internal consistency: α = 0.72 (body image)– 0.92 (physical functioning) [36]; α = 0.73 (body image)– 0.92 (physical functioning) [37]; α = 0.73 (body image)– 0.91 (chest symptoms) [38]; α = 0.82 (treatment issues)– 0.96 (physical functioning, career concerns) [40].

Reliability– test-retest: all domains had good reliability [36, 37, 39]. This is confirmed by the results of another study, which calculated intraclass correlation coefficients (ICC = 0.83 [95%CI (0.74; 0.88)] (social functioning)– 0.98 [95%CI (0.96; 0.98)] (interpersonal relationships)) [38].

Construct validity (comparison between other instruments): the tool had satisfactory results of convergent validity with SF-36 [36, 38], SGRQ [37], UKSIP [39]. No statistically significant correlations were found between CFQoL and most of WHOQoL-BREF [37].

Construct validity (comparison between subgroups): CFQoL discriminates between different levels of disease severity (determined by FEV₁%) [36, 38, 39].

Responsiveness (comparison before and after antibiotic therapy lasting 2 weeks): several significant differences with large effect sizes across the 7 out of 9 domains (d > 0.80). Moderate effect sizes were across the treatment burden (d = 0.56) and career (d = 0.59) [36].

Q-Life

1 [50]

Internal consistency: reliability of individual Q-Life scores was high (at least 3 personal items were described, N = 223)– α = 0.83.

Reliability– test-retest: ICC = 0.90 [95%CI (0.65; 0.92)].

Construct validity (comparison between other instruments): overall Q-Life scores were positively correlated with CFQ-R respiratory domain score (r = 0.57, p < 0.001) and overall CFQ-R scores (r = 0.71, p < 0.001).

Responsiveness (comparison after treatment with a product containing elexacaftor/tezacaftor/ivacaftor): Q-life scores (N = 123)– MD = 20.8 [95%CI: (17.5; 25.0) p < 0.001]. Median overall Q-life scores at baseline, 3 and 6 months were 65.0, 84.2 and 87.5, respectively.

AWESCORE

1 [49]

Reliability– test-retest: ICC (for total score) = 0.989 [95%CI (0.979; 0.994)], ICC (for individual domains) = 0.87 [95%CI (0.775; 0.931)] (mood)– 0.97 [95%CI (0.947; 0.985)] (weight).

Construct validity (comparison between other instruments): the tool had satisfactory results of convergent validity with CFQ-R 14+.

Construct validity (comparison between subgroups): total score was significantly higher (MD = 25 [95%CI: (22; 28)]) for the 183 clinically stable participants (N = 183) compared to the participants with an exacerbation (N = 63).

Responsiveness (comparison between clinical stable vs. exacerbation groups): a significant reduction in AWESCORE total score was indicated between clinical stability and exacerbation groups– MD = -30 [95%CI: (-32; -25)]. Significant reductions were observed in all domains (p < 0.001).

CAT

1 [48]

Internal consistency: α = 0.89 (total score).

Construct validity (comparison between other instruments): the tool had satisfactory results of convergent validity with other tools (SGRQ, CFQ-R 14+).

UKSIP

1 [39]

Internal consistency: α = 0.87 (total score).

Reliability– test-retest: the Spearman’s rank correlation coefficients ranged from 0.57 to 0.84 (all domains had acceptable level of reproducibility).

Construct validity (comparison between subgroups): limited ability to observe differences between disease severity groups (no significant differences were found between severe and moderate groups).

SIG scale

1 [47]

Reliability (test-retest): ICC = 0.78 [95%CI (0.59; 0.88)].

Criterion validity: sensitivity and specificity of a SIG compared to a 50% threshold for CFQoL was 93% [95%CI (87; 97)] n/N = 100/107)] and 64% [95%CI (39; 84) n/N = 9/14] (for SIG score ≥ 5). The area under the ROC curve was 0.84. Increasing the threshold of a SIG scale to ≥ 6 reduced the sensitivity to 82% and increased the specificity to 78% (11/14).

Construct validity (comparison between subgroups): SIG scale was weakly correlated with FEV₁% (r = 0.21).

PQLS

1 [46]

Structural validity: three domains were separated (task interference, psychological, physical function).

Internal consistency: α = 0.82 (physical domain)– 0.83 (psychological/task interference domains).

Reliability– test-retest: the Pearson correlation coefficients ranged from 0.52 to 0.78 (all domains had acceptable level of reproducibility).

Construct validity (comparison between other instruments): the tool had satisfactory results of convergent validity with other tools (SOBQ, SF-36).

Construct validity (comparison between subgroups): PQLS total score was correlated with disease severity (6MWT distance and FEV₁%)– worse PQLS score associated with shorter 6MWT distance and lower FEV₁%.

SGRQ

1 [45]

Internal consistency: α = 0.49 (impact subscale)– α = 0.87 (activity subscale).

Construct validity (comparison between subgroups): SGRQ discriminates between different degrees of disease severity (determined by FEV₁%).

FLZ^M

2 [41, 43]

Structural validity: 18 questions were separated (in a modified version of the questionnaire intended for patients with cystic fibrosis FLZ^M-CF) [43].

Internal consistency: FLZ^M total score of general life satisfaction– α = 0.72, FLZ^M total score of satisfaction with health– α = 0.77 [41]. FLZ^M-CF total score of general life satisfaction– α = 0.73, FLZ^M-CF total score of general health satisfaction– α = 0.85 [43].

Construct validity (comparison between subgroups): low correlation between FLZ^M-CF and FEV₁%. Limited ability to observe differences between subgroups

​ [41, 43].

SF-36

2 [41, 42]

Structural validity: eight domains were separated, in accordance with the original design of the tool [41].

Internal consistency: α = 0.78 (general health)– 0.93 (physical functioning) [41]; α = 0.82 (social functioning)– 0.91 (physical functioning) [42].

Construct validity (comparison between subgroups): SF-36 does not discriminate between different levels of disease severity (determined by FEV₁%) sufficiently enough to detect progressive changes present in CF [41, 42].

PLC

1 [41]

Internal consistency: α = 0.72 (sense of belonging to others)– 0.93 (capacity).

Construct validity (comparison between other instruments): in comparison to SF-36 and FLZ^M the tool achieved the most favorable results in psychosocial domains.

Construct validity (comparison between subgroups): significant correlations were found between absence of pulmonary symptoms and all PLC domains. Significant correlations were also found between FEV₁% and capacity domain (rs = 0.50).

CRDQ

1 [44]

Structural validity: three domains were separated (in the final version of the questionnaire, it was decided to exclude the fourth domain: dyspnoea).

Internal consistency: α = 0.78 (dyspnoea)– 0.93 (fatigue).

Reliability (test-retest): correlations were good for most of all (14/15) items.