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Optometrist-led diabetic clinics audited: in the fourth article of OT's new audit series, specialist optometrist Sarah Farrell explores the efficiency and safety of diabetic maculopathy clinics in Bedfordshire.

Background

Diabetic patients who are screened in the Bedfordshire Diabetic Eye Screening Programme (BDESP) and subsequently graded as M1 according to NHS Diabetic Eye Screening Program (NDESP) protocol (1) traditionally enter the hospital eye service and are seen in a consultant-led medical retina clinic. Large numbers of these referrals in Bedfordshire have meant increased waiting times and as these patients must be seen within 13 weeks according to NDESP protocol, this causes a delay in the scheduled appointments for other medical retina patients.

An optometrist-led diabetic maculopathy (M1) clinic was established by Moorfields at Bedford in May 2010, with the primary aim to reduce the number of false positive M1 referrals resulting in a consultant-led appointment. In addition, these clinics have been used to manage those patients with confirmed M1 status but who do not require ophthalmological intervention, such as those illustrated in Figure 1.

The patient in Figure 1 was referred with a M1 grade; confirmed as Ml on an optometrist's examination, but does not require any ophthalmological intervention.

Patients deemed suitable for optometrist-led clinics are:

* R1M1 grade at retinopathy screening

* Normal vision ([greater than or equal to] 6/12) or vision loss without obvious clinically significant maculopathy (ie no circinate exudates at the macula or extensive haemorrhaging).

M1 referrals with poor vision (<6/12) or obvious clinically significant maculopathy (circinate exudate/extensive haemorrhaging) are automatically seen in a consultant-led clinic. This is the same for R2 and R3 patients regardless of M grading (M0/M1).

[FIGURE 1 OMITTED]

Optometrists perform dilated slit lamp biomicroscopy of the posterior segment and evaluate a macula scan OCT for all patients referred to the Ml clinic.

Audit objectives

Part 1: To calculate the false positive referral rates to optometrist-led Ml clinics and the adherence of optometrist-led Ml clinics to NDESP Quality Assurance Standards regarding waiting times.

Part 2: Evaluate the sensitivity and specificity of the optometrist-led Ml clinics by conducting a blind sample comparison of optometrist grading to gold standard (consultant ophthalmologist) using review of OCT images.

Standards

The details of the NHS Diabetic Eye Screening Programme Quality Assurance Standards Release 7, Version 1.3, January 23 2012 (1) are detailed below (Table 1).

NHS Diabetic Eye Screening Programme Workbook Release 4.4, January 23 2012 Section 8 (2) Maculopathy (M1) is defined as:

* Exudate within 1 disc diameter (DD) of the centre of the fovea

* Circinate or group of exudates within the macula

* Retinal thickening within 1 DD of the centre of the fovea (if stereo available)

* Any microaneurysm or haemorrhage within 1DD of the centre of the fovea only if associated with a best VA of

[less than or equal to] 6/12 (if no stereo). Liverpool diabetic eye study (3)

* 84% sensitivity and 89% specificity was achieved for mydriatic 35mm film photography.

Gloucestershire diabetic eye study (4)

* 87.8% sensitivity and 86.1% specificity achieved for mydriatic digital photography.

A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy (Olson et al) 5

* 73% sensitivity and 90% specificity achieved by optometrists using slit lamp examination.

There are currently no standards set for the use of OCT either in isolation or in addition to slit lamp examination for maculopathy detection.

Methodology

Part 1: All patients seen in the optometrist-led M1 clinic between 19/5/2010-30/3/2011 were included for analysis. Electronic patient records were retrospectively reviewed. Data retrieved included: referral grade (M0/ M1) per eye, optometrists grade (M0/ M1) per eye, date screened, date seen for optometrist appointment, outcome (laser/FFA/ophthalmology review/ optom-M1 review/discharge), date of listing and date of laser (if done).

Each case was classified into one of the following categories:

* 'True False Positive' = referred with M1 grade, M0 grade on examination (non-diabetic lesion at the macula eg drusen)

* 'False positive to ophthalmological intervention' = referred with M1 grade, M1 grade confirmed at optometrist clinic but does not require ophthalmological intervention (no laser, FFA or ophthalmology review required)

* 'True maculopathy' = referred with M1 grade which is confirmed in optometrist clinic and does require ophthalmological intervention (laser, FFA or ophthalmology review).

Part 2: A total of 22 patients (44 eyes) from the audit period were randomly selected by the medical retina consultant (considered 'gold standard') to evaluate the sensitivity and specificity of the optometrist-led clinics. As most referrals from screening are made with a unilateral diagnosis of M1, this provided the scope for measuring specificity (ability to correctly identify normal eyes or M0). Eyes were graded according to NDESP Protocol (1) by a consultant ophthalmologist. Patient identification, referral grade and the optometrist's grade was invisible to the ophthalmologist. False positive, false negative rates were calculated (sensitivity and specificity deduced).

Results

Part 1: Outcomes

A total of 128 patients were referred with an M1 grade during the audit period. Of these, 20 had a bilateral Ml grade. The total number of eyes referred with an M1 grade was 148.

Outcomes following optometrist assessment are shown in Table 2.

Waiting times

Objective 8: Average time from screening to optometrist M1 consultation (time between notification of positive test and consultation): 46 days

* 98% (126/128) seen within 13 weeks: Achievable standard exceeded Objective 11: To ensure timely treatment of those listed by the ophthalmologist (time between listing and first laser treatment following screening, if listed at first visit): 20 days (range 0-49)

* 100% (9/9) listed in <10 weeks: Achievable standard exceeded Objective 12: To minimise overall delay between screening event and first laser treatment (time between screening encounter and first laser treatment, if listed at first visit): 74 days

* 100% (9/9) completed laser treatment in <15 weeks: Achievable standard exceeded.

Part 2: Overall grading agreement between optometrist and consultant ophthalmologist in blind sample comparison: 36/44 = 82%

False positive rate (represents a grading of M1 by optometrist but M0 by ophthalmologist) was 2/28 or 7% (specificity 93%).

The false negative rate (M0 grading by optometrist but M1 by ophthalmologist) was 4/16 or 25% (sensitivity 75%).

Conclusion

* There are large numbers of false positive referrals from BDESP into ophthalmology (true false positives 42%) and the majority of referrals for M1 do not require immediate ophthalmological intervention (89% discharged or managed by optometrist)

* Optometrist-led Ml clinics have high levels of grading specificity and create very low numbers of false positive referrals (7%). There was a good level of sensitivity for detecting Ml (75%) and this is in line with previous studies (5).

Interestingly, the use of OCT does not appear to increase sensitivity levels compared with optometrists using slit lamp examination alone (5); however, it is worth noting that the sample size used for sensitivity calculations in this audit was small (n=16) and the blind sample comparison was completed with consultant using OCT images only

* Moorfields at Bedford's optometrist-led M1 clinic is exceeding all targets set by the NDESP for waiting times and does not cause any significant delay in laser treatment when needed

* Optometrist-led Ml clinics can provide a safe way of reducing the number of false positive referrals resulting in a consultant-led clinic thereby allowing for shorter waiting times and increased capacity for higher risk patients. Optometrists are ideally placed to be involved in the longer-term follow up of M1 patients

* The introduction of Ophthalmic Photographic Diabetic Review (OPDR) clinics in April 2013 by NDESP (6) will allow screening programmes to suspend some patients from annual screening without initiating a referral to the HES. This additional step is primarily for those who may require more frequent photographic review and could provide a welcome reduction to the number of false positive M1 referrals to the HES.

Unfortunately, a lack of funding from the NHS Commissioning Board for the use of OCT in these clinics (the integration of which must be agreed and funded locally via clinical commissioning groups) means that OPDR services may not realise their potential which, according to these findings, could be to manage as many as 89% of Ml referrals.

Audit recommendations

* There is a need for ongoing quality assurance of optometrist's work. Following the completion of this audit, a method of continuous audit has been established for each optometrist operating in the Ml clinic. Every fourth patient is evaluated retrospectively by consultant ophthalmologist using OCT images, as in part 2 of this audit. Results are regularly analysed and used for optometrist training and development and a report submitted annually to Moorfields Clinical Audit Board

* A repeat of part 1 of this audit is being conducted to compare false positive referral rates (both true and to ophthalmology) for those Ml referrals that went straight to consultant-led clinics during the same audit period, and adherence to NDESP protocol for waiting times for these patients.

References

(1) NHS Diabetic Eye Screening Programme Quality Assurance Standards Release 7, Version 1.3, 23 January 2012 http://diabeticeye. screening.nhs.uk/standards

(2) NHS Diabetic Eye Screening Programme Workbook Release 4.4, 23 January 2012 Section 8. Intervention and treatment. http://diabeticeye. screening.nhs.uk/workbook-section8

(3) Harding SP, Broadbent DM, Neoh C, White MC, Vora J. Sensitivity and specificity of photography and direct ophthalmoscopy in screening for sight threatening eye disease: the Liverpool Diabetic Eye Study. Bmj 1995; 311(7013): 1131

(4) Scanlon PH, Malhotra R, Thomas G, Foy C, Kirkpatrick JN, Lewis-Barned N, et al. The effectiveness of screening for diabetic retinopathy by digital imaging photography and technician ophthalmoscopy. Diabet Med 2003; 20(6) 467-74

(5) Olson JA, Strachan FM, Hipwell JH, Goatman KA, McHardy KC, Forrester JV, et al. A comparative evaluation of digital imaging, retinal photography and optometrist examination in screening for diabetic retinopathy. Diabet Med 2003; 20(7): 528-34.

(6) "Moving all Diabetic Eye Screening Programmes to a Common Pathway" NHS Diabetic Eye Screening Programme Version 1.2, 07 March 2012 http://diabeticeye.screening. nhs.uk/pathway
Table 1
NHS Diabetic Eye Screening Programme Quality Assurance
Standards Release 7, Version 1.3

Standard Standard expected for M1 grades

To ensure timely consultation for Minimum standard: 70% <13/52, 95%
all screen positive patients <18/52 Achievable standard: 95%
(objective 8) <13/52

To ensure timely treatment of Minimum standard: 70% <10/52
those listed by ophthalmologist Achievable standard: 95% <10/52
(objective 11)

To minimise overall delay between Minimum standard: 70% <15/52, 95%
screening event and first laser <18/52 Achievable standard: 95%
treatment (objective 12) <15/52

Table 2
*14 patients (16 eyes) required intervention: Nine FFA
(six needed laser post FFA), three had laser (no FFA) and two
were referred to consultant-led clinics (no laser or FFA)

Outcome Number of eyes Percentage

True false positives (M0 grade) 63/148 42%

False positives to ophthalmology 69/148 47%
(but correctly referred with M1)
Total number of referrals for M1 132/148 89%
suitable for discharge or
optometrist management
Total number of M1 referrals 16/148 11%
requiring ophthalmology intervention *
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Title Annotation:CLINICAL AUDIT
Author:Farrell, Sarah
Publication:Optometry Today
Geographic Code:4EUUK
Date:Oct 19, 2012
Words:1804
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