Psychometric Properties of Preference-Based Measures for Economic Evaluation in Amyotrophic Lateral Sclerosis: A Systematic Review

Table 1

Description of included studies.

Author (year)

Country

Study design

Study purpose

Study setting

Sample size (N)

Sample characteristics

ALS severity or diagnosis

Preference-based measurement used

Mean ± SD for measurement

Known-group validity

Convergent validity

Floor effect

Evaluation of measurement properties

Ilse et al. (2015) [29]

Germany

Cross-sectional study

To describe the relationship between HRQL using the EQ-5D, disease severity, and social support in patients with ALS

Outpatient clinic

N = 49

Age 63.8 ± 10.0, 49% female, disease duration 35.1 months ±36.3, time since diagnosis not presented, ALSFRS-R 32.6 ± 9.2 (range 0–48)

Severity classified according to ALSFRS-R 32.6 ± 9.2 (range 0–48)

EQ-5D-3L, EQVAS

EQ-5D 0.36 ± 0.29 EQVAS 42.8 ± 24.1

Bulbar-onset patients had a significantly higher EQ-5D score (median 46.4) than limb-onset patients (median 14.9)

EQ-5D^a:+FSozU K-14^b (r = 0.43, ), +BDI (r = −0.43), +ALSFRS-R (r = 0.72, )

61–86% of individuals with ALS reported moderate/severe problems in EQ-5D dimensions compared to 3-28% in general population

Not assessed: primary objective was not to assess psychometric properties of generic preference-based measure

Jones et al. (2014) [30]

UK

Longitudinal clinical trial

To assess whether ALS clinical staging could be used in cost-effectiveness analyses

10 outpatient clinics

N = 214

Age 58.1 ± 10.8, 31% female, time since diagnosis not presented, ALSFRS-R score not presented

ALS severity not presented, diagnosis classified according El Escorial criteria: definite (n = 82, 38%), probable (n = 80, 37%), probable laboratory supported ALS (n = 38, 17%), possible (n = 14, 5%)

EQ-5D-3L, EQVAS

EQ-5D score not presented for total sample

Mean EQ-5D scores decreased with increasing ALS severity^c: from 0.65 (less severe) to 0.27 (more severe)

ALS clinical stage is a predictor of EQ5D score (χ² 145.08,  = 3.14 x 10^32)

Not available

Not assessed: primary objective was not to assess psychometric properties of generic preference-based measure

Winter et al. (2010) [31]

Germany

Cross-sectional study

To compare HRQL in patients with ALS, FSHD, and MG and to identify the determinants of HRQL in each disease

7 outpatient clinics

Total N = 91, ALS N = 37

Age 59.6 ± 11.0, 43% female, time since diagnosis 39.7 months ± 73.7, ALSSS 27.1 ± 6.8 (range 0–40)

Severity classified according to the ALSSS 27.1 ± 6.8 (range 0–40)

EQ-5D-3L, EQVAS

EQ-5D 0.54 ± 0.32 (median 0.70), EQVAS 0.38 ± 0.15 (median 0.40)

Mean EQ-5D scores were significantly lower in ALS (0.54) compared to FSHD (0.75) and MG (0.89)

ALSSS significantly associated with EQ-5D

70–92% of individuals with ALS reported moderate/severe problems in EQ-5D dimensions compared to 3–28% in general population

Not assessed: primary objective was not to assess psychometric properties of generic preference-based measure

López-Bastida et al. (2009) [32]

Spain

Cross-sectional study

To determine the economic burden (direct and indirect costs) and assess HRQL in patients with ALS in Spain

Multiple outpatient clinics across 7 regions

N = 63

Age 59.1 ± 10.3, 48% female, time since diagnosis 44.6 months ±62.4, ALSFRS-R score not presented

Severity classified according to high^d or low^e severity: high severity (n = 47, 75%), low severity (n = 16, 25%)

EQ-5D-3L, EQVAS

EQ-5D 0.18 ± 0.22, EQVAS 0.29 ± 0.23

High severity: EQ-5D 0.12 ± 0.17, EQVAS 26 ± 22 low severity: EQ-5D 0.35 ± 0.27, EQVAS 38 ± 23 EQ-5D scores decreased with increasing ALS severity from 0.35 to 0.12

Not available

Not available

Not assessed: primary objective was not to assess psychometric properties of generic preference-based measure

Green et al. (2003) [33]

UK

Cross-sectional study

To examine the relationship between disease severity, HRQL, and health state values in patients with MND

2 outpatient clinics

N = 77

Age 58.1 ± 12.1 (range 27–79), 36% female, time since diagnosis 25.3 months ±22.6 (range 1–112), ALSFRS-R score not presented

Severity classified according to the ALS/HSS: level 1 mild (n = 15, 20%), level 2 moderate (n = 21, 27%), level 3 severe (n = 22, 29%), level 4 terminal (n = 19, 25%)

EQ-5D-3L, EQVAS

EQ-5D 0.35 ± 0.35, (95% CI 0.27–0.43) (median 0.31), EQVAS 0.55 ± 0.22 (95% CI 0.5–0.6) (median 0.50)

Mean EQ-5D scores decreased with increasing ALS severity from 0.63 to −0.01

EQ-5D^f: +EQVAS (r = 0.60^g); +ALSPM (r = −0.60^g), +ALSADL/I (r = −0.75^g), +ALSED (r = 0.19^g), +ALSCOM (r = −0.32^g), +ALSER (r = −0.43^g)

Not available

Not assessed: primary objective was not to assess psychometric properties of generic preference-based measure

Kiebert et al. (2001) [34]

UK

Cross-sectional study

To assess HRQL and health state values in a sample of patients with different levels of severity of ALS

2 outpatient clinics

N = 77

Age 58.1 ± 12.1 (range 27–79), 36% female, time since diagnosis 25.3 months ±22.6 (range 1–112), ALSFRS-R score not presented

Severity classified according to the ALS/HSS: level 1 mild (n = 15, 20%), level 2 moderate (n = 21, 27%), level 3 severe (n = 22, 29%), level 4 terminal (n = 19, 25%)

EQ-5D-3L, EQVAS

EQ-5D score not presented for total sample, EQVAS 0.55 ± 0.22 (median 0.5)

The percentage of total sample who endorsed the worst response options of the EQ-5D increased with ALS severity across all dimensions; mean EQVAS scores decreased with increasing ALS severity from 0.74 to 0.37

Not available

54–80% of individuals with ALS reported moderate/severe problems in 4/5 EQ-5D dimensions (exception of 27% of people for anxiety/depression)

Not assessed: primary objective was not to assess psychometric properties of generic preference-based measure

Sherwood-Smith et al. (2000) [35]

USA

Cross-sectional study

To determine the concurrent validity of three self-administered HRQL questionnaires in patients with ALS

Outpatient clinic

N = 19

Age 60.5 (range 36–76), 42% female, time since diagnosis 20.5 months (range 2–62), ALSFRS-R score not presented, FVC 64% (range 17%–91%)

ALS severity not presented, diagnosis classified according to the El Escorial criteria: definite (n = 9, 47%), probable (n = 4, 21%), possible (n = 5, 26%), suspected (n = 1, 5%)

QWB-SA

QWB-SA 0.43 (range 0-1)

Not available

QWB^a: +SIP/ALS (r = 0.55), +SF-36 (r = 0.21)

Not available

Methodological quality^h: adequate Rating^i: sufficient (inconsistent based on majority) grading of quality of evidence^j: very low

HRQL: health-related quality of life, EQ-5D: EuroQol Five Dimension, EQVAS: EuroQol Visual Analogue Scale, ALSFRS-R: Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised, BDI: Beck Depression Inventory, ALSSS: Amyotrophic Lateral Sclerosis Severity Scale, MG: myasthenia gravis, FSHD: facioscapulohumeral muscular dystrophy, MND: motor neuron disease; ALSAQ-40 :ALS Assessment Questionnaire 40 subscales; ALSPM: physical mobility, ALSADL/I: activities of daily living/independence; ALSED: eating and drinking; ALSCOM: communication; ALSER: emotional reactions, ALS/HSS: ALS Health State Scale; FVC: forced vital capacity, QWB-SA: Quality of Well-Being Self-Administered Scale, SF-36: Short Form 36, SIP/ALS-19: Sickness Impact Profile ALS-19. Range of health utility scores from −0.306–0.885, with higher scores representing better health [36]. ^aSpearman’s rank correlation coefficient. ^bMeasures social support. ^cProposed clinical stages developed by Jones et al. estimated using ALSFRS-R scores and modified King’s ALS staging system to indicate ALS severity. ^dHigh severity: patients needed caregiver’s assistance. ^eLow severity: patients did not need caregiver’s assistance. ^fPearson’s product-moment correlation coefficient. ^gCorrelation is significant at the 0.01 level (two-tailed). ^hDetermined using COSMIN’s risk of bias checklist²⁷. ⁱResults rated against COSMIN’s criteria for good measurement properties²⁶: 50% of correlations (QWB: +SIP/ALS (r = 0.55), +SF-36 (r = 0.21)) in accordance with hypotheses, results rated as sufficient with an inconsistent rating from the majority of results. ^jDetermined using the GRADE approach. More details are described in detail in the COSMIN manual²⁶.