Elicitation of Health State Utility Values in Retinitis Pigmentosa by Time Trade-off in the United Kingdom

Figures & data

Table 1 Demographic Characteristics of Participants in TTO Interviews (n=110) and UK public^20–25

TTO Interview Demographics	n	%	UK Public Demographics	%
18 to 25	11	10.00%	18 to 29	19.77%
26 to 35	20	18.18%	30 to 39	17.06%
36 to 45	20	18.18%	40 to 49	16.41%
46 to 55	17	15.45%	50 to 59	17.31%
56 to 65	19	17.27%	60 to 64	7.09%
66 to 75	16	14.55%	65 to 74	12.83%
76 to 85	7	6.36%	75 to 89	9.53%
Female	56	50.91%	Female	50.48%
Male	54	49.09%	Male	49.52%
Single	38	34.55%	Single	34.99%
Married	56	50.91%	Married or civil partnered	50.63%
Divorced	9	8.18%	Divorced	7.96%
Widowed	7	6.36%	Widowed	6.42%
Degree-level education	33	30.00%	Degree-level education	29.92%
A-Level education	33	30.00%	A-level secondary education or other higher/further non-degree-level education	30.45%
GCSE-level education	23	20.91%	GCSE secondary education	20.33%
Other education level	21	19.09%	Other education or no education or do not know	19.30%
Scotland	5	4.55%	Scotland	8.15%
North West	11	10.00%	North West	10.98%
Yorkshire and the Humber	5	4.55%	Yorkshire and the Humber	8.24%
North East	4	3.64%	North East	4.00%
Wales	2	1.82%	Wales	4.72%
West Midlands	7	6.36%	West Midlands	8.89%
East Midlands	2	1.82%	East Midlands	7.25%
East of England	2	1.82%	East of England	9.35%
South West	4	3.64%	South West	8.44%
Greater London	14	12.73%	Greater London	13.42%
South East	16	14.55%	South East	13.74%
Full-time employment	55	50.00%	Working full-time	50.34%
Part-time employment	10	9.09%	Working part-time	9.24%
Not employed	21	19.09%	Not working	18.66%
Retired	24	21.82%	Assumed retired (age ≤65)	21.76%

Note: educational level represents the furthest level achieved by each TTO interview participant. Geographical regions are top-level subdivisions of the United Kingdom as per the International Territorial Level classification system; these regions represent where TTO interview participants were resident at the time of recruitment.

Abbreviations: A-level, Advanced Level qualification studied at ages 16–18 (non-compulsory); GCSE, General Certificate of Secondary Education studied at ages 14–15 (compulsory); TTO, time trade-off.

Table 2 TTO Utility Value per Health State

Result	n	Mean	SD	Median	SE	95% CI
“Moderate impairment”	110	0.78	0.20	0.85	0.02	0.74	0.82
“Severe impairment”	110	0.65	0.25	0.70	0.02	0.60	0.70
“Profound impairment”	110	0.50	0.27	0.50	0.03	0.45	0.55
“Counting fingers”	110	0.43	0.28	0.44	0.03	0.38	0.48
“Hand motion” to “no light perception”	110	0.33	0.26	0.30	0.03	0.28	0.38

Notes: “Moderate impairment” health state defined as VA better than 20/200 or VF radius of greater than 10°. “Severe impairment” health state defined as VA from 20/200 to 20/500 or VF radius of 6° to 10°. “Profound impairment” health state defined as VA from 20/500 to 20/1250 or VF radius of 2° to 6°. “Counting fingers” health state defined as VA from 20/1250 to 20/20,000 or VF radius of less than 2°. “Hand motion” to ‘no light perception’ health state defined as VA worse than 20/20,000.

Abbreviations: CI, confidence interval; n, sample size; SD, standard deviation; SE, standard error; TTO, time trade-off.

Figure 1 TTO utility value per health state (n=110 responses to each). “Moderate impairment” health state defined as VA better than 20/200 or VF radius of greater than 10°. “Severe impairment” health state defined as VA from 20/200 to 20/500 or VF radius of 6° to 10°. “Profound impairment” health state defined as VA from 20/500 to 20/1250 or VF radius of 2° to 6°. “Counting fingers” health state defined as VA from 20/1250 to 20/20,000 or VF radius of less than 2°. “Hand motion” to “no light perception” health state defined as VA worse than 20/20,000.

Abbreviations: n, sample size; TTO, time trade-off; VA, visual acuity; VF, visual field.

Table 3 VAS Score per Health State

Result	n	Mean	SD		Median	SE	95% CI
Own health today	110	73.28	16.82		77.00	1.60	70.10	76.46
“Moderate impairment”	110	47.95	15.38		45.00	1.47	45.04	50.85
“Severe impairment”	110	37.55	14.87		35.00	1.42	34.74	40.37
“Profound impairment”	110	27.31	12.73		25.00	1.21	24.90	29.72
“Counting fingers”	110	23.09	12.70		20.00	1.21	20.69	25.49
“Hand motion” to “no light perception”	110	17.22	12.49		15.00	1.19	14.86	19.58

Notes: “Moderate impairment” health state defined as VA better than 20/200 or VF radius of greater than 10°. “Severe impairment” health state defined as VA from 20/200 to 20/500 or VF radius of 6° to 10°. “Profound impairment” health state defined as VA from 20/500 to 20/1250 or VF radius of 2° to 6°. “Counting fingers” health state defined as VA from 20/1250 to 20/20,000 or VF radius of less than 2°. “Hand motion” to ‘no light perception’ health state defined as VA worse than 20/20,000.

Abbreviations: CI, confidence interval; n, sample size; SD, standard deviation; SE, standard error; VAS, visual analogue scale.

Figure 2 VAS score per health state (n=110 responses to each). “Moderate impairment” health state defined as VA better than 20/200 or VF radius of greater than 10°. “Severe impairment” health state defined as VA from 20/200 to 20/500 or VF radius of 6° to 10°. “Profound impairment” health state defined as VA from 20/500 to 20/1,250 or VF radius of 2° to 6°. “Counting fingers” health state defined as VA from 20/1,250 to 20/20,000 or VF radius of less than 2°. “Hand motion” to ‘no light perception’ health state defined as VA worse than 20/20,000.

Abbreviations: n, sample size; VAS, visual analogue scale.

Table 4 Comparison of Health State Utility Values from the Current Study and Existing literature¹⁰

	Current Study	Lloyd et al 2019
Health State	TTO	EQ-5D-5L	HUI3
“Moderate impairment”	0.78	0.71	0.52
“Severe impairment”	0.65	0.62	0.36
“Profound impairment”	0.50	0.52	0.22
“Counting fingers”	0.43	0.35	0.14
“Hand movement” to “no light perception”	0.33	0.15	−0.04

Lloyd A, Piglowska N, Ciulla T, et al. Estimation of impact of RPE65-mediated inherited retinal disease on quality of life and the potential benefits of gene therapy. Br J Ophthalmol. 2019;103(11):1610–1614.

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