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Original article
The economic cost of posterior capsule tear at cataract surgery
  1. Dania Qatarneh,
  2. Rashmi G Mathew,
  3. Simon Palmer,
  4. Catey Bunce,
  5. Stephen Tuft
  1. Moorfields Eye Hospital NHS Foundation Trust, UK
  1. Correspondence to Stephen Tuft, Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London EC1V 2PD, UK; s.tuft{at}ucl.ac.uk

Abstract

Purpose To estimate the direct financial burden to healthcare purchasers of a posterior capsule tear (PCT) during cataract surgery.

Methods A retrospective data analysis of cataract surgeries was performed. Patients who had surgery in the 2-year period from April 2005, with a maximum follow-up, to April 2009 were identified. Patients previously under review for ocular comorbidity apart from cataract were excluded. Each case with PCT was matched with an uncomplicated cataract operation performed on the same list by the same grade of surgeon. For both groups, we extracted details of all additional subsequent visits and interventions. Data on the cost of visits and procedures were provided by the Department of Health. We then compared this data between groups.

Results A total of 100 patients with PCT were matched with 100 controls. The preoperative parameters of the two groups were similar. The cases required a median of 3 (mean 3.6, range 0–24) additional postoperative visits compared with 0 (mean 0.19, range 0–8) for controls, with a median duration of follow-up of 74 (mean 129.5, range 6–1316) days for cases compared to 21 (mean 26.1, range 0–308) days for controls (p=0.000). The average cost of extra visits was £475.0 (SD £697.8) for cases and £69.2 (SD £51.0) for controls (p<0.001).

Conclusions Based on the National Health Service national tariff, a PCT during cataract surgery results in significant additional financial cost to healthcare purchasers. A full cost analysis would be required to estimate the additional cost of a PCT for the healthcare provider.

  • Cataract
  • costs and cost analysis
  • complications
  • treatment surgery

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Introduction

Cataract extraction is one of the commonest surgical procedures performed within the National Health Service (NHS). Although the operation carries a low risk and has a high expectation for an improved quality of life, complications occur and these can have visual and economic consequences. In this study, we have focused on the effect of posterior capsule tear (PCT) because it is easily identified during surgery and it is an event that should be documented in the surgical record. It is also a relatively common complication, particularly during surgical training, with an overall rate that in the UK has reduced in the decade from 1997, from 4.4%1 to 1.9%.2 Treatment at the time of surgery includes excision of any vitreous that has prolapsed forward from the posterior segment, removal of residual lens fragments and insertion of an intraocular lens (IOL). The IOL may be implanted at a second procedure and loss of capsule support may mean that an IOL can no longer be placed within the capsular bag. When a PCT occurs, there is an increased risk of postoperative complications such as endophthalmitis, pseudophakic retinal detachment or cystoid macular oedema that can adversely affect the visual outcome. Inevitably, some patients who have had a PCT require additional postoperative review and they may need further surgical intervention. To the best of our knowledge, the cost of providing this additional care has not been estimated.

In the UK public sector, the healthcare purchasers are currently the Primary Care Trusts. To determine the additional economic cost to the healthcare purchasers associated with PCTs, we performed a retrospective comparison of the outcome of 100 cases with PCT and 100 controls that had cataract surgery without a PCT. To restrict the study to a measure of the direct results of the cataract surgical episode, we excluded patients who were already under review for pre-existing pathology (eg, glaucoma, diabetic retinopathy). We then counted the number of additional hospital visits for all patients in both groups and estimated the mean cost of these episodes using published data for the average national tariff.

Methods

We obtained institutional review board approval for this study. Patients were identified from an electronic database of approximately 9000 cataract surgery procedures. Cases were defined as patients who had cataract surgery complicated by a PCT with or without an anterior vitrectomy. A control patient for each case was then selected, defined as a patient who underwent uncomplicated cataract surgery performed on the same day as the case by a surgeon of the same grade (consultant, fellow or specialist registrar). Only one eye per patient was included in the study. Exclusion criteria for both cases and controls were the presence of ocular comorbidity identified before cataract surgery that would require specific review appointments thereafter (eg, diabetic retinopathy, glaucoma, macular degeneration). Patients with surgical complications apart from a PCT (eg, zonular dehiscence, suprachoroidal haemorrhage) were also excluded.

All operations were performed within a 2-year interval from April 2005 with a maximum follow-up of to April 2009. Surgery was performed within a dedicated cataract surgery service by a number of surgeons across four outreach centres within the Moorfields Eye Hospital NHS Foundation Trust. Surgeons used the same data entry system (Epatient®) and followed the same general management guidelines agreed within the Trust. Visual acuities were recorded in Snellen notation using the best available refraction. For both cases and controls, the clinical notes and the patient administration system were reviewed to identify all subsequent visits. The nature of any surgical complications was confirmed, the number of follow-up visits counted and any subsequent interventions recorded. We did not identify and include additional visits made to other hospitals outside the Trust, general practitioners or to other healthcare providers. Follow-up was defined as the interval in days between cataract surgery and the final recorded visit.

The indicative costs of attendances and the various additional procedures were obtained from the Department of Health reference cost guidance using NHS Health Resource Group (HRG) version 4 and 2009 data; these figures were based on the national tariff with an average national market forces factor (MFF).3–5 Minor variations of procedures were grouped within each of these HRGs (table 1). In this system, the cost of each attendance or procedure is quoted as a standard figure irrespective of the individual costs of additional investigations, materials or medications provided. Therefore, any additional treatment required for the immediate management of a PCT during cataract surgery, for example an anterior vitrectomy, is not passed on to the healthcare purchasers but is covered by the healthcare provider (eg, hospital or clinic). For the purposes of this study, we defined a cataract care package as a preoperative assessment, the surgical procedure and one postoperative review in clinic. The cost of additional postoperative care for each patient was then calculated as the total cost of all outpatient visits and admissions for surgery beyond this care package.

Table 1

HRG classification and cost of relevant procedures

Comparisons between groups were made using a two-tailed paired t test. Visual acuity results were grouped as either Snellen acuity 6/12 or better, 6/18 to 6/60 and worse than 6/60, and comparisons made using a Wilcoxon signed rank test. A p value of 0.05 was taken as statistically significant. The results of this study were extrapolated to national data using published results from previous audits of cataract surgery in the UK.

Results

We excluded 20% of potential case/control pairs because either the case or the control had ocular comorbidity. All patients had their surgery performed by phacoemulsification. An analysis of the 100 cases with PCT and the 100 uncomplicated control patients confirmed that before surgery the two groups were similar for age, gender and axial length (table 2). However, the visual acuity recorded before surgery was slightly worse in the cases than in the controls although this was not statistically significant (p=0.119). The patients that had a PCT during cataract surgery required significantly more postoperative visits spread over a longer period of follow-up than did the controls (p<0.001). Patients with PCT had a median of three additional visits (range 0–24 visits) compared with a median of 0 visits (range 0–8 visits) for the uncomplicated controls. The median follow-up for cases was 74 days (range 6–1316 days) compared to 21 days (range 0–308) for controls. The maximum follow-up for a case (1316 days) was for management of secondary chronic uveitis and for a control (308 days) was for management of postoperative cystoid macular oedema. However, at the time of final review the corrected visual acuity of the two groups was similar (p=0.165). No case with a PCT had a final visual acuity of worse than 6/60.

Table 2

Patient characteristics

In the 100 cases, a total of 22 additional surgical procedures were performed on 17 eyes at a later date. This total included 3 anterior vitrectomies (coded BZ12Z), 15 pars plana vitrectomies (12 coded BZ21Z and 3 coded BZ22Z), 2 secondary IOL insertions (coded BZ03Z), 1 wound resuturing (coded BZ02Z) and 1 intravitreal injection (coded BZ24Z). The total additional cost of these 22 procedures using the 2009–2010 national tariff with average MFF was £20 768. Using the 2009–2010 national tariff with MFF, the average cost of additional care beyond the standard cataract surgery package was £69.2 (SD £51.0) for controls and £475.0 (SD £697.8) for cases (difference £405.8).

In the UK, there were 321 512 phacoemulsification procedures performed in the year 2009–2010.6 This figure is reduced to approximately 295 000 procedures if patients less than 60 years are excluded. A recent prospective multicentre audit of 55 567 operations with data collected in the period 2001–2006 (86% of the operations performed between 2004 and 2006) reported that in 71.5% of eyes no cause for a guarded visual prognosis was recorded preoperatively,2 while a previous survey of 18 454 patients 50 years of age or greater operated in 1997 reported that 72% of eyes had no comorbidity.1 Therefore, it is reasonable to estimate that 211 000 operations were performed in 2009–2010 on eyes in which cataract was the only pathology. With an incidence of PCT of 1.9%, there would then have been 4007 cases with PCT at an additional cost of £1 626 274. Using this data, if the rate of PCT could be reduced to 1%, the saving to healthcare purchasers would be £855 934 per annum.

Discussion

A PCT is the most common visually significant complication of cataract surgery, which in turn is the most frequently performed ophthalmic procedure in the NHS. A PCT is also suited to cost analysis because it is normally recorded in the clinical record, and it is a complication with a range of potential adverse outcomes. To identify the associated costs, we have used data based on the HRGs provided by the Department of Health.7 We have confirmed that when a PCT occurs during otherwise routine cataract surgery, the average duration of follow-up and the number of additional interventions is significantly increased. As a result, there were substantial differences in the average cost of routine cataract surgery compared to surgery complicated by a PCT. However, the cost differences were not as high as we had anticipated, because the majority of additional visits were as outpatients, which cost only 5% of some surgical interventions. It is of note that the cost of a PCT will rise for the period 2010–2011 because the tariff for vitreoretinal procedures (HRG groups BZ21Z and BZ22Z) will increase (table 1). An increased tariff means that the cost of the 22 additional interventions required for our cases after PCT would increase by 54% from £20 768 to £32 085.

Other studies have examined the cost implications of complications of ophthalmic surgery, most often based on claims for reimbursement.8–10 When calculated from insurance payments to Medicare beneficiaries, the cost associated with cystoid macular oedema after cataract surgery was reported to be 47% higher than those of controls,8 while the cost of managing cases with endophthamitis after cataract surgery was 1.45 times higher.9 In patients who have proliferative vitreoretinopathy there is a doubling of the cost of retinal detachment surgery.11 The additional costs incurred by inpatient treatment for endophthalmitis compared to outpatient treatment are significant,10 12 although inpatient treatment is not part of the management protocol for PCT.

In this study, we have only analysed the direct costs to the healthcare purchasers of a PCT. The cost of consumables and additional investigations were itemised but not costed separately, as they are included as part of the outpatient or surgical package. Any additional costs associated with poor vision, extra visits to general practitioners, transport, loss of independence, etc have also not been calculated, although poor vision in the elderly may be associated with falls, and these in turn will have associated costs for healthcare purchasers.7 Interestingly, we did not demonstrate a difference between groups for the final visual acuity, although previous studies generally conclude that a PCT has an adverse effect on the visual outcome.13 If this is the case, then non-correctable visual loss following PCT would also have an impact on quality of life when measured as trade-offs14 or health-related quality of life.15 16

This study design has some limitations. We matched cases and controls according to the day of surgery and the grade of surgeon but, despite this, the preoperative visual acuity tended to be worse in the cases that had a PCT, possibly due to the presence of denser cataract at the time of surgery in this group. We also limited the study to eyes without pre-existing comorbidity in an attempt to isolate the effect of a PCT. The effect of a PCT in eyes with comorbidity such as diabetic retinopathy or subretinal neovascularisation was not estimated, although visually significant complications are also likely. Sources of recruitment bias were not examined. For example, a PCT is normally recorded in the electronically because it is defined as a ‘critical incident’, but we did not perform an audit to confirm that all cases were recorded. It is possible that minor cases of PCT may not have been entered in the database with a potential bias of the study to more severe complications. Finally, we have used a figure of 1.9% as the national rate of PCT, although this figure may be lower in eyes with no associated pathology.17

There is a natural desire to reduce the incidence of PCT because it can have an adverse visual impact on the patient. Our results show that reducing the incidence of this complication would also reduce the direct costs of cataract surgery for the healthcare purchaser. A full cost analysis would be required to determine the financial implication of PCT for the healthcare provider, and whether these costs are fully recovered from the purchaser. Encouragingly, there is evidence that the rate of PCT in the UK has reduced between 1997 and 2006.1 2 A further reduction will have implications for cost savings that could potentially offset any additional costs of training. With the proposed introduction of Best Practice Tariffs or Preferred Patient Pathways in the UK, where there would be a unit cost for a cataract procedure including follow-up, there will be an economic saving if the costs that result from surgical complications can be reduced. Whereas at present the burden of additional cost is recovered from the purchasers (primary care trusts), in the future the providers (clinics or hospital trusts) would only be paid a unit cost for the entire cataract episode, and any additional treatment costs associated with a higher than expected complication rate would mean that these procedures were performed at a financial loss.18 19

References

Footnotes

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Moorfields Eye Hospital NHS Foundation Trust.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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