We congratulate Salowi and colleagues on their study of the use of
CUSUM to monitor competency in cataract extraction (1). However there are
two modifications that could make their system more responsive and
reliable.
Firstly the authors use a CUSUM chart that fluctuates on only one
side of the zero line. Traditionally CUSUM charts fluctuate on both sides
of the zero line (2,3). The consultant in their Figure 1...
We congratulate Salowi and colleagues on their study of the use of
CUSUM to monitor competency in cataract extraction (1). However there are
two modifications that could make their system more responsive and
reliable.
Firstly the authors use a CUSUM chart that fluctuates on only one
side of the zero line. Traditionally CUSUM charts fluctuate on both sides
of the zero line (2,3). The consultant in their Figure 1 performed 48
procedures and 43 were successful while 5 were failures. The weight for a
failure would be -1.791666 and for a success it would be 0.208333.
Figure 1 depicts the traditional CUSUM graph with this data. Against this,
the data from his trainee is also drawn. The trainee CUSUM score keeps
going further and further away from the zero line, suggesting that he has
not reached the bottom of his learning curve. Once his learning is over,
his mean CUSUM line will run parallel to the zero line.
The second modification relates to the decision interval. The authors
discuss in detail the arbitrary decision intervals (control lines) that
they have employed, based on a trade-off between the need to detect poor
performance quickly and that to avoid a large number of false alarms.
Decision lines need not be arbitrary. With the help of computers,
bootstrapping techniques can be employed, so that these lines are placed
where they are statistically meaningful. As an illustration, in Figure 1
with the consultant performance, there were 5 failures and 43 successes.
The 5 failures need not be evenly interspersed among the successes. The
sequence of failures is purely a matter of chance and 2 or even 3 failures
may be clustered together. Bootstrapping allows random reordering of the
failures and successes in a way that the overall numbers of success and
failures are the same for each iteration. The computer can calculate the
maximum and minimum score for each iteration. If a 1000 iterations are
performed it is possible to calculate the mean of the highest scores
(maximum score in the iteration) and the mean of the lowest scores
(minimum score in the iteration) and also the standard deviation around
the means. The upper decision line is the limit drawn with the mean upper
score plus 2SD. The lower decision line is the mean lower score minus 2SD.
If surgery is performed by a person of comparable competence as the
consultant, his CUSUM score will lie within the two decision lines, 95% of
the time.
We have recently used CUSUM for a clinical trial and for this we
developed software that allows for easy bootstrapping, drawing of control
lines and plotting of CUSUM score. This software is available free on the
internet. (http://jacob.puliyel.com/foresee/).
Figure 2 can also be redrawn using the acceptable rate for posterior
capsule rupture (PCR) of 5%. Here the acceptable standard is 1 failure for
19 successes. For Figure 3 using the acceptable rate for impaired vision
as 10% (using data reported by the authors from the Malaysian National
Cataract Surgery Registry) there can be 1 failure for 9 successes.
The software is interactive and allows CUSUM plotting in real time
(meaning that it allows one to see how the CUSUM graph evolves, with each
new success or failure). We hope that the free software available on the
net will encourage more widespread use of CUSUM in various clinical
situations.
Figure 1 Standard reference cumulative sum (CUSUM) showing
performance by a trainee and a consultant can be viewed at
http://jacob.puliyel.com/#paper_199
Reference
1. Salowi MA, Choong YF, Goh PP, Ismail M, Lim TO. CUSUM: a dynamic
tool for monitoring competency in cataract surgery performance. Br J
Ophthalmol. 2010;94:445-9.
2. Van Rij AM, McDonald JR, Pettigrew RA, Putterill MJ, Reddy CK,
Wright JJ. Cusum as an aid to early assessment of the surgical trainee. Br
J Surg. 1995;82:1500-3.
3. Sibanda T, Sibanda N. The CUSUM chart method as a tool for
continuous monitoring of clinical outcomes using routinely collected data.
BMC Med Res Methodol. 2007;7:46.
Ashish Puliyel, Tech Guru gonzoBuzz, Singapore
ashishpuliyel@gmail.com
Jacob Puliyel, Consultant Pediatrician, St Stephens Hospital, Delhi, India
puliyel@gmail.com
Conflict of Interest:
The CUSUM software available free on the internet, was developed by the authors in the context of a clinical trial.
One concept of the PEARS/ WEHE schemes was to increase equity of
access to eye care services across Wales. Any successful scheme which
achieves an increase in access will increase cost, at least in the short-
term, but can prove to be more cost-effective since more expensive
downstream-treatments are avoided as a result of earlier intervention and
patient outcomes are likely...
One concept of the PEARS/ WEHE schemes was to increase equity of
access to eye care services across Wales. Any successful scheme which
achieves an increase in access will increase cost, at least in the short-
term, but can prove to be more cost-effective since more expensive
downstream-treatments are avoided as a result of earlier intervention and
patient outcomes are likely to be enhanced.
Purchasers must judge whether improved access for patients justifies the small additional cost per case (c. £12-15) and improved access results in more patients being seen in secondary care. In the evaluation, 66% of patients were managed entirely by optometrists without referral to the Hospital Eye Service (HES): previously, these patients may have contributed to unnecessary referrals. Other benefits for patients include convenience, reduced travel time, reduced anxiety and fewer mis-diagnoses.
The change in total cost of primary and secondary eye care following the introduction of these schemes was not quantified. This would have required a randomised protocol comparing costs between intervention and control groups and incorporating a before and after design to capture detailed patient-level data.
Optometrists registered on the schemes at the time of the evaluation had completed seven distance learning modules, four case history scenarios and a clinical-skills assessment. We utilised the results of the evaluation to determine the nature of the re-accreditation training. Optometrists were required to complete six distance learning modules and pass OSCE assessments based on communication, clinical examination and referral. Tutorials were held for those optometrists, identified in the evaluation, who had made inappropriate patient-management decisions. The current cost of training for accreditation is approximately £200 per optometrist. The impact of this one-off cost is minimal given the number of patients seen under the scheme and was therefore not included in the model.
We hope these comments have further clarified patient-centred
benefits of the schemes.
The Primary Eyecare Acute Referral Scheme, PEARS was introduced in
Wales in in 2003. We welcome the paper by Sheen et al since this presents
an opportunity for the scheme to be appraised and costed.
The authors are open about the weaknesses of their study, such as the
poor response rate to letters sent to GPs. However, there are still
considerable uncertainties about the accuracy of the costings....
The Primary Eyecare Acute Referral Scheme, PEARS was introduced in
Wales in in 2003. We welcome the paper by Sheen et al since this presents
an opportunity for the scheme to be appraised and costed.
The authors are open about the weaknesses of their study, such as the
poor response rate to letters sent to GPs. However, there are still
considerable uncertainties about the accuracy of the costings. It is
likely that the provision of this service will have generated an increase
in the number of patients seen in ophthalmic primary care and a consequent
increase in the number of referrals to the HES thereby increasing costs.
No data is presented in this respect although this could have been sought
from GP or hospital databases.
The authors conclude that the net cost of the scheme is between 10GBP
and 15GBP per patient. What is not made sufficiently clear is that this
is ADDITIONAL cost to the purchaser. PCTs should be discouraged from
implementing this service without first identifying extra funding. It
should not be expected that this service can be paid for from savings made
in the budgets of ophthalmic units.
No mention is made of the training required before optometrists can
embark upon this scheme. It would have been helpful for those considering
such a scheme to have some idea of the nature of and the costs of such
training.
Yours faithfully,
Simon Longstaff
Chairman
Ophthalmic Group Committee
Conflict of Interest:
I am the chairman of the Ophthalmic Group Committee
Sub-Tenon block is a safe, efficient and effective technique for
delivering local anaesthesia for phacoemulsification cataract surgery.[1]
Several studies have compared sub-Tenon's block with topical anaesthesia
for intra-operative pain complications and the technique is found to be
favourable.[2] We are not aware of any published study that has assessed
post-operative pain (beyond 30 minutes post-...
Sub-Tenon block is a safe, efficient and effective technique for
delivering local anaesthesia for phacoemulsification cataract surgery.[1]
Several studies have compared sub-Tenon's block with topical anaesthesia
for intra-operative pain complications and the technique is found to be
favourable.[2] We are not aware of any published study that has assessed
post-operative pain (beyond 30 minutes post-operatively) for routine
phacoemulsification using sub-Tenon's block.
We devised a questionnaire-based survey and asked 56 consecutive
patients to comment on their experience of pain after routine and
uneventful cataract surgery. Surgery was performed by one surgeon (TCD)
and the sub-Tenon's was performed by one anaesthetist (CMK) in all cases.
All patients received sub-Tenon's block using a 2.54cm long metal
posterior sub-Tenon's cannula and 4 cc of 2% lidocaine was used. The
questionnaire was designed to explore parameters of post-operative pain
including severity, character, duration and associated symptoms. Severity
was assessed using a visual analogue score from 0 (no pain) to 10 (severe
pain). The patients were interviewed on the second post-operative day by
telephone. The patients were also asked about any previous eye surgery and
whether they were taking painkillers concomitantly for any other
conditions.
Our results revealed that 51 (91%) patients had suffered no pain
after surgery. However, 31 (61%) were on regular analgesics for other
medical conditions whereas 20 (39%) were not taking any painkillers at
all. Forty one patients had undergone previous cataract surgery. Of the
five patients (9%) who suffered post-operative pain; 2 described immediate
onset, with 1 patient each describing onset at 30 minutes, 2 hours and 24
hours after surgery respectively. Of these, 1 patient had spontaneous
relief, whereas the other 4 required oral analgesia.
There was no notable correlation between those on regular analgesia
and post-operative pain, however, the design and retrospective nature of
the study precludes any conclusions from being drawn in this regard. A
prospective, randomised controlled trial addressing these parameters in
the future would be ideal.
We conclude that our survey supports other studies that the sub-
Tenon's block is not only safe, effective and efficient but also provides
good post-operative pain relief after routine phacoemulsification cataract
surgery.
Dear Editor,
We read the paper by Chadha and Wright on small margin excision of periocular basal cell carcinoma (BCC) with interest. (1)The authors justify the use of small margins, without margin control (excision and closure without confirmation of histologically clear margins) by their low recurrence rates over a follow up period ranging from 37-59 months.
There has been extensive debate on the ideal approach to...
Dear Editor,
We read the paper by Chadha and Wright on small margin excision of periocular basal cell carcinoma (BCC) with interest. (1)The authors justify the use of small margins, without margin control (excision and closure without confirmation of histologically clear margins) by their low recurrence rates over a follow up period ranging from 37-59 months.
There has been extensive debate on the ideal approach to the patient with a suspicious skin lesion. We consider the issues here to be two fold:
complete tumour removal and reduced recurrence rate and these two have been linked in most studies.(2) The next dilemma for most of us is to determine factors affecting subclinical tumour extension to achieve a complete removal with minimum excision of healthy tissue. Mohs micrographic surgery is considered the gold standard as it is shown to achieve a 98% 5-year cure rate (1773 cases of BCC).(3) Modifications have been sought due to the stringent training and processing requirements of the original technique and acceptable results have been achieved with staged ‘Slow Mohs’ (4) and multi-stage fast paraffin sections; (5)with maybe a varying of the margins based on tumour morphology.(6)
Data from this study would suggest a tumour debulking (excision and closure without margin control) would be equally effective in terms of final outcomes of recurrence rates, as the authors make no attempt to ensure complete removal. Recurrence in patients reported to have complete excision (2.6%, 2/78) is the other argument for this being an acceptable approach. However, interestingly their data also shows an incomplete excision rate ranging from 11.9% (single stage) and 17.4% (two stage excision group presumed to be larger lesions) and a clinical recurrence rate of 2.6% for complete excision versus 14.3% in incomplete excision group (followed up only) and 0% having undergone further excision to ensure complete removal. Also, these recurrence rates stated are for less than 5 years and survival curves may help in estimating the true incidence.
There is good evidence to support a policy of retreatment of incompletely excised tumours especially when they present at critical sites, the deep surgical margins are involved, histology shows a more aggressive subtype and surgical defect is repaired using flaps and grafts.(7) We must not forget recurrences put the patient in a higher risk group being more difficult to evaluate, with more aggressive and larger invasive tumours needing more extensive excision second time round. Recurrence rates of 10% are not considered acceptable in routine primary eyelid tumours where the functional and cosmetic outcomes have much more significant implications than elsewhere in the body.(8)
We understand the service pressure in the National Health Service or elsewhere but quality of care to the patients should be our ultimate aim. A service adaptation to increase efficiency with more appropriate use of the minor outpatient theatres for small lesions not needing major reconstruction, discharge from eye clinics earlier than the mandatory 5 years with follow-up in primary care clinics/ even GP surgeries can ensure complete tumour removal without increasing the service load. The added advantage of reduced patient anxiety and surgeon confidence cannot be under-estimated as these may actually increase the follow up visits much more than the already higher number proposed by the authors in presence of an incomplete excision.
References:
1. Chadha V, Wright M. Small margin excision of periocular basal cell carcinomas. Br J Ophthalmol 2009; 93: 803-806.
2. Cook BE, Bartley GB. Treatment options and future prospects for the management of eyelid malignancies. An evidence-based update. Ophthalmology 2007; 108:
2088-2100.
3. Mohs FE. Micrographic surgery for the microscopically controlled excision of eyelid cancers. Arch Ophthalmol 1986; 104: 901-909.
4. Morris DS, Elzaridi E, Clarke L, Dickinson AJ, Lawrence CM. Periocular basal cell carcinoma: 5 year outcome following Slow Mohs surgery with formalin-fixed paraffin-embedded sections and delayed closure. Br J Ophthalmol 2009;
5. Khandwala MA, Lalchan SA, Chang BYP, Habib M, Chakrabarty A, Cassels Brown A. Outcome of periocular basal cell carcinoma managed by overnight paraffin section. Orbit 2005; 24: 243-247.
6. Hsuan JD, Harrad RA, Potts MJ, Collins C. Small margin excision of periocular basal cell carcinoma: 5 year results Br J Ophthalmol 2004; 88: 358-360.
7.Telfer NR, Colver GB, Morton CA. Guidelines for the management of basal cell carcinoma. Br J Dermat 2008; 159: 35-48.
8. Anderson RL. Micrographic technique Arch Ophthalmol 1986; 104: 818-819.
Thank you for your comment.
In our manuscript, we did not use the mean and the standard deviation but used each patient's raw data for the analyses. Further, as written in the methods section, we only used unpaired Student's t test (parametric test) for the comparison between the two groups and paired Student's t test (parametric test) for the comparison between the baseline and each follow-up point.
Thank you for your comment.
In our manuscript, we did not use the mean and the standard deviation but used each patient's raw data for the analyses. Further, as written in the methods section, we only used unpaired Student's t test (parametric test) for the comparison between the two groups and paired Student's t test (parametric test) for the comparison between the baseline and each follow-up point.
We have read with great interest the article by Unoki N et al Randomised controlled clinical trial of sub-tenon triamcinolone as an adjunct to panretinal photocoagulation for the treatment of diabetic retinopathy 1. We wish to make few comments.
The p value of the primary outcome as documented is 0.04. But if calculated from the results documented, applying parametric tests as used in the study it co...
We have read with great interest the article by Unoki N et al Randomised controlled clinical trial of sub-tenon triamcinolone as an adjunct to panretinal photocoagulation for the treatment of diabetic retinopathy 1. We wish to make few comments.
The p value of the primary outcome as documented is 0.04. But if calculated from the results documented, applying parametric tests as used in the study it comes out to be highly significant 0.001. We would like to know whether authors might have used a non-parametric test for the analysis.
In the retinal thickness analysis, the p values mentioned are significant for the foveal and perifoveal thickness. Again we calculated the p values applying the parametric tests and it came out to be without statistically significant difference. We feel the use of non-parametric test for the analysis could have been more appropriate because the data especially of that of retinal thickness is a continuous variable.
References
1. N Unoki, K Nishijima, M Kita, K Suzuma, D Watanabe, H Oh, T Kimura, A Sakamoto and N Yoshimura. Randomised controlled trial of posterior sub- Tenon triamcinolone as adjunct to panretinal photocoagulation for treatment of diabetic retinopathy. Br. J. Ophthalmol. 2009; 93; 765-770.
2. Techniques for scatter and local photocoagulation treatment of diabetic retinopathy: Early Treatment Diabetic Retinopathy Study Report no. 3. The Early Treatment Diabetic Retinopathy Study Research Group. Int Ophthalmol Clin, 1987 Winter;27(4):254-64.
I was interested to read the editorial on vision screening by Evans,
Smeeth and Fletcher [1]. I share their concern that, despite the
availability of free eye tests for the older population, over 50% of
vision impairment is due to easily correctable conditions.
I recently audited an elderly person health check; an annual
assessment of the medical, social, and physical needs of all patie...
I was interested to read the editorial on vision screening by Evans,
Smeeth and Fletcher [1]. I share their concern that, despite the
availability of free eye tests for the older population, over 50% of
vision impairment is due to easily correctable conditions.
I recently audited an elderly person health check; an annual
assessment of the medical, social, and physical needs of all patients over
75 years at a GP practice in Wirral.
Whilst an assessment of vision formed part of the pro forma carried
out by the health care assistant, this was self reported and recorded
broadly; no visual symptoms, provision of spectacles, profound impairment
one eye, and profound impairment both eyes.
As part of the audit cycle, for one month, all patients attending
their health check had their visual acuity measured (with and without
pinholes) using a Snellen chart. Additionally, attendance at optician for
regular eye check was recorded.
24 patients attended for their elderly person health check, excluding
4 patients who had significant ocular pathology (3 with age related
macular degeneration, 1 had recent cataract surgery), 55% were female and
mean age of 80.2 years.
13 patients (65%) had some visual impairment, 4 patients (20%)
improved with pinholes. Similarly, van der Pols et al [2] reported that
vision improved with pinholes in 22.6% of a national sample of British
elderly, and Wormald et al [3] reported improvement in 27% of their
subjects (elderly people living in central London). Full refraction and
revised prescription may be of benefit to these patients. 19 patients
(95%) had regular eye tests at their optician. The one patient who did
not attend regularly was found to have a vision impairment that improved
with pinholes. This patient was advised to see their optician for
refraction.
The editorial concluded that complementary approaches, facilitated
around a primary care hub, may reduce the levels of treatable vision
impairment in older people. This small audit suggests that, despite the
findings of recent clinical trials, primary care may still have a role in
the prevention of treatable vision impairment, albeit a small one;
essentially to educate patients and remind them to attend their opticians
regularly.
Competing interests: None.
References
1) Evans J, Smeeth L, Fletcher A. Vision screening. British Journal
of Ophthalmology 2009; 93: 704-705.
2)van der Pols JC, Bates CJ, McGraw PV, et al. Visual acuity
measurements in a national sample of British elderly people. British
Journal of Ophthalmology 2000; 84:165-170.
3)Wormald RP, Wright LA, Courtney P, Beaumont B, Haines AP. Visual
problems in the elderly population and implications for services. British
Medical Journal 1992; 304: 1226-9.
We read with great interest the article by Mariotti et al. estimating
the global prevalence of trachoma. For the country of Egypt, the article
refers only to the published survey in Menofiya Governorate in the Nile
Delta, suggesting that only this single governorate is endemic for
trachoma. This is far from the case, however, as two other studies shed
light on trachoma in other areas of Egypt. Both studies were presen...
We read with great interest the article by Mariotti et al. estimating
the global prevalence of trachoma. For the country of Egypt, the article
refers only to the published survey in Menofiya Governorate in the Nile
Delta, suggesting that only this single governorate is endemic for
trachoma. This is far from the case, however, as two other studies shed
light on trachoma in other areas of Egypt. Both studies were presented
and reported in the meetings of the WHO Alliance for the Global
Elimination of Trachoma by 2020 for the years 2004 & 2005 and
submitted to the Ministry of Health & Population. A population based
survey of trachoma (sample size = 4,500) was conducted in Menia
Governorate (3.5 million) in 2002; among children age 2-10 years the
prevalence of active trachoma was 42% while among adults age 50+ the
prevalence of trachomatous trichiasis was 6.2%. This survey has formed
the basis for interventions by the Ministry of Health and the Al Noor
Foundation to address trachoma in Upper Egypt. Separately, a Trachoma
Rapid Assessment was carried out in 15 villages in Fayoum Governorate in
2003. This work identified trachoma as a severe public health problem
in these communities with village prevalence of active disease among
children (ages 2-10) ranging from 15.9% to 85.2%. Similar to Menia,
trichiasis was common with 7.7% of adults age 50+ having trichiasis. In
both of these settings, and throughout much of rural Egypt, the conditions
with encourage trachoma transmission are still evident—poor sanitation and
poor facial cleanliness being the most notable.
Clearly, there is a need for more systematic epidemiologic surveys
and mapping of trachoma in Egypt in order to estimate the prevalence of
active trachoma and trichiasis in the country. The current evidence from
Egypt, however suggests that the figures presented in the paper by
Mariotti and colleagues is a significant underestimate of the distribution
and magnitude of the trachoma in the country.
We congratulate Salowi and colleagues on their study of the use of CUSUM to monitor competency in cataract extraction (1). However there are two modifications that could make their system more responsive and reliable.
Firstly the authors use a CUSUM chart that fluctuates on only one side of the zero line. Traditionally CUSUM charts fluctuate on both sides of the zero line (2,3). The consultant in their Figure 1...
Authors response
Dear Sir,
One concept of the PEARS/ WEHE schemes was to increase equity of access to eye care services across Wales. Any successful scheme which achieves an increase in access will increase cost, at least in the short- term, but can prove to be more cost-effective since more expensive downstream-treatments are avoided as a result of earlier intervention and patient outcomes are likely...
Sir,
The Primary Eyecare Acute Referral Scheme, PEARS was introduced in Wales in in 2003. We welcome the paper by Sheen et al since this presents an opportunity for the scheme to be appraised and costed.
The authors are open about the weaknesses of their study, such as the poor response rate to letters sent to GPs. However, there are still considerable uncertainties about the accuracy of the costings....
Dear Editor,
Sub-Tenon block is a safe, efficient and effective technique for delivering local anaesthesia for phacoemulsification cataract surgery.[1] Several studies have compared sub-Tenon's block with topical anaesthesia for intra-operative pain complications and the technique is found to be favourable.[2] We are not aware of any published study that has assessed post-operative pain (beyond 30 minutes post-...
Dear Editor, We read the paper by Chadha and Wright on small margin excision of periocular basal cell carcinoma (BCC) with interest. (1)The authors justify the use of small margins, without margin control (excision and closure without confirmation of histologically clear margins) by their low recurrence rates over a follow up period ranging from 37-59 months.
There has been extensive debate on the ideal approach to...
Conflict of Interest:
...Dear editor,
We have read with great interest the article by Unoki N et al Randomised controlled clinical trial of sub-tenon triamcinolone as an adjunct to panretinal photocoagulation for the treatment of diabetic retinopathy 1. We wish to make few comments. The p value of the primary outcome as documented is 0.04. But if calculated from the results documented, applying parametric tests as used in the study it co...
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Dear editor,
I was interested to read the editorial on vision screening by Evans, Smeeth and Fletcher [1]. I share their concern that, despite the availability of free eye tests for the older population, over 50% of vision impairment is due to easily correctable conditions.
I recently audited an elderly person health check; an annual assessment of the medical, social, and physical needs of all patie...
We read with great interest the article by Mariotti et al. estimating the global prevalence of trachoma. For the country of Egypt, the article refers only to the published survey in Menofiya Governorate in the Nile Delta, suggesting that only this single governorate is endemic for trachoma. This is far from the case, however, as two other studies shed light on trachoma in other areas of Egypt. Both studies were presen...
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