Cost and detection rate of glaucoma screening with imaging devices in a primary care center

Figures & data

Figure 1 Definition of positive and negative results at screening.

Note: A positive result was defined as the presence of at least 2 tests outside normal limits.
Abbreviations: IOP, intraocular pressure; HRT, Heidelberg retina tomograph; ONLs, outside normal limits.

Figure 2 The distribution of subjects with the 2 different detection strategies: conventional detection and telemedicine screening with imaging devices.

Abbreviations: OH, ocular hypertension; PACG, primary closed-angle glaucoma; POAG, primary open angle glaucoma; XFG, pseudoexfoliation glaucoma; PCC, primary care center.

Table 1 Classification criteria

Diagnosis	IOP (mmHg)	Optic disc	Visual field
Normal	<22	Normal	Normal
OH	≥22	Normal	Normal
Probable glaucoma	Any	Glaucomatousb	Normal
	Any	Normal	Glaucomatousa
Glaucoma	Any	Glaucomatousb	Glaucomatousa

Notes:

a Glaucomatous field: 3 contiguous locations outside normal limits in the pattern deviation plot.

b Glaucomatous optic disc: presence of rim thinning, and/or cup/disk asymmetry of >0.3 and/or disk hemorrhage and/or nerve fiber layer defect. Based on direct examination at the slit lamp, disk photographs, HRT, and GDx images.

Abbreviations: GDx, nerve fiber analyzer; HRT, Heidelberg retina tomograph; IOP, intraocular pressure; OH, ocular hypertension.

Table 2 Demographics of the participants

Variable	Population	Randomly selected screening sample	Subjects included and examined at screening program (randomly selected and invited to participate)	Subjects examined by current detection method (belong to same population but entered the detection process spontaneously with no prior selection)
Subjects >40 years	23,527	1,599	414	165
Age (years) mean ± SD (range)	63.37±10.61 (40–100)	63.29±14.73 (40–100)	65.2±11 (40–93)	70.2±9.8 (43–94)
40–49 (%)	5,256 (22.3)	358 (22.4)	50 (12.0)	8 (4.8)
50–59 (%)	4,947 (21.0)	336 (21.0)	69 (16.7)	12 (7.3)
60–69 (%)	4,886 (20.8)	332 (20.7)	135 (32.6)	52 (31.5)
70–79 (%)	4,361 (18.5)	297 (18.5)	107 (25.9)	64 (38.8)
80–89 (%)	3,226 (13.7)	219 (13.6)	52 (12.6)	28 (17.0)
90–99 (%)	851 (3.6)	58 (3.6)	1 (0.2)	1 (0.6)
Gender (%)
Women	14,155 (60.2)	986 (61.6)	249 (60.1)	106 (64.2)
Men	9,372 (39.8)	613 (38.3)	165 (39.9)	59 (35.8)

Abbreviation: SD, standard deviation.

Table 3 Degree of glaucoma in detected cases

Variable	Screening program	Conventional detection
Mean deviation (range)	−3.54±2.63 (−10.31 to −0.14)	−5.52±7.18 (−25 to 0)
Visual field index (range)	97.85±2.20 (94 to 100)	81.92±21.32 (25 to 100)
Degree of glaucoma according to mean defect (dB)
Initial, 0 to −6	15 (88.23%)	14 (56%)
Moderate, −6.1 to −15	2 (11.77%)	5 (20%)
Advanced, <−15.1	–	6 (24%)

Table 4 Estimated individual costs

Type of exam/location	Activity	Cost (€)
Primary care center	Admission/reception	3.57
	Primary care visit	10.18
	Structural cost	1.96
Ophthalmology at primary care center	Admission/reception	3.57
	Optometry visit	5.43
	Ophthalmology visit	6.23
	(including material)
	Structural cost	1.96
Glaucoma screening at primary care centera	Examination (technician and nurse)	31.37
	Instruments	10.69
	Training subject information	8.54
Glaucoma visit at hospital	Glaucoma consultationb (includes infrastructure =20%)	55.41
	Fundus photograph	37.44
	Visual field	15.94
	Pachymetry	17.74

Notes:

a This cost was calculated by optimizing the use of instruments and staff for a larger scale screening program.

b Data obtained from previous costs calculations.^13,14

Table 5 Cost of glaucoma screening and conventional detection

Variable	Screening in selected sample	Estimated screening in 1 million	Conventional detection in population
Sample/population
Subjects	1,563	1,000,000	46,838
Cases examined
Subjects	414	502,305	932
Primary care visits
Subjects		130,052	932
Cost/visit			15.70
Total cost			14,632.4
Ophthalmic visit at primary care
Subjects			677
Cost/visit			18.69
Total cost			12,653.13
Ophthalmic visit at primary care with tests (visual field + optic disc photograph)
Subjects			165
Cost/visit			52.37
Total cost			8,641.05
Screening program visits at primary care centre with tests (HRT, GDx)
Subjects	414	130,052
Cost/visit	50.60	38.7
Total cost	20,946.90	5,036,949.4
Glaucoma consultations at hospital with tests (visual field + optic disc photograph + gonioscopy)
Subjects	24	7,539	45
Cost/visit	126.53	126,5	126.53
Total cost	3,036.72	954,022.9	5,693.85
Total cost	23,983.62	5,990,972.3	41,620.43

Abbreviations: GDx, nerve fiber analyzer; HRT, Heidelberg retina tomograph.

Table 6 Detection rate and cost per case detected

Variable	Screening with imaging devices (sample)	Screening applied in the NHS to 1 million subjects. Screening examination cost of 38.7€/persona	Conventional detection (population)
Population		1,000,000	46,838
Population >40 years	1,563	502,305	23,527
Subjects examined (A)	414	130,052	932
Glaucoma cases detected (B)	17	5,340	29
Glaucoma detection rate (B/A)	4.1	4.1	3.1
Total cost (C)	23,983.6	5,990,972.3a	41,620
Cost/case detected (C/B)	1,410.8	1,121.8	1,435.1

Notes:

a This cost was calculated by optimizing the use of instruments and staff for a larger scale screening program. B: cases classified as glaucoma or probable glaucoma.

Abbreviation: NHS, National Health Survey.

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