Introduction

Visual impairment is a significant problem both for the affected individual and society in economic and social terms. According to the latest data from the World Health Organization, it is estimated that 39 million people worldwide are blind. The most significant cause of preventable blindness is cataract [1][2].

Prevalence rates of cataracts and blindness globally depend on the examination method, such as Lens Opacities Classification System (LOCS) III or Optical Quality Analysis System (OQAS), and diagnostic cut-off value used for best corrected visual acuity (VA) or presenting VA. However, the risk of cataracts increases with each decade of life, starting around age 40. Half of white Americans had cataracts by 75 years of age in 2010. It is forecasted that the number of people with cataracts will double from 24.4 million to about 50 million by the year 2050 [3]. Results from Europe vary significantly, depending on the region, population, examination method, etc. The study from 2013 reflects this difference, from 6% in the Netherlands to almost 70% in Spain [4]. The most recent study from Sweden showed that the crude prevalence was 31.5%, with a higher percentage in the male population [5]. In Serbia, cataract was the second most frequent reason for hospitalizations in females in 2017, after breast cancer [6].

Cataract surgery is one of the most often performed surgical interventions in developed countries. The predominant method of cataract surgery in Western countries is phacoemulsification. In randomized clinical trials, it produces better outcomes than extracapsular cataract extraction (ECCE) [7]. However, the ECCE method remains prevalent in developing countries due to its cost-effectiveness [8].

The WHO has suggested that an annual rate of 350 surgeries per 100,000 inhabitants is a useful target against cataract blindness [9].

This study aimed to compare the cost-effectiveness of two cataract surgery techniques, phacoemulsification and ECCE, by considering the occurrence of possible complications of the operation from the perspective of the health insurance (third-party payer).

Methods

The data for the analysis was obtained from the Department of Ophthalmology of the General Hospital Kruševac, Serbia. The hospital is the only public hospital that provides healthcare services for approximately 260,000 people in the Rasina district.

This study covered one year (from March 2019 to February 2020). During the study period, a total of 1,179 cataract surgeries (1,123 phacoemulsifications and 56 EC-CE) were performed by five surgeons. All interventions were included in the analysis. Data on the efficacy of these two methods were calculated from patients' medical records. The retrospective analysis determined the number of patients with complications of cataract surgery that occurred in one or the other surgery method. This study was approved by the hospital's Ethical Committee (No. 09/21 EO from April 19, 2021).

The cost-effectiveness of two types of cataract surgery was evaluated using the decision tree (Figure 1).

Figure 1 Decision tree used in the model. ECCE – extracapsular cataract extraction.

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Probabilities

As the analysis outcome, complications during and after surgery were observed. In the phacoemulsification group, 146 out of 1,123 (13%) patients had complications, with 77% of posterior capsule opacification as the main complication. In the ECCE group, 43% of patients had complications, dominantly lens dislocation, occurring in 29% of cases. Probabilities for all outcomes and both techniques of surgery are presented in Figure 1.

Costs

Only direct costs were considered in the analysis. All costs are expressed in Serbian dinars (RSD), for which an exchange rate was as follows: 1 EUR = 117.5736 RSD for the year 2021, according to the National Bank of Serbia. Cost data were taken from the administrative documentation at the hospital and the official price list of health services of the Republic Institute for Health Insurance [10]. In the analysis, the following costs were included: the first consultation with an ophthalmologist, at which the indication for cataract surgery and scheduling of the operation itself happened; admission for surgery (Table 1); costs of the procedure itself (Table 2); follow-up controls after one and three weeks of the surgery; capital cost for the phacoemulsification machine.

Table 1. Costs on admission to the hospital prior to surgery included in the analysis (independent of the technique performed).

Variable	Number of units	Unit cost RSD	Total cost RSD
Specialist consultation	1	186.98	186.98
Topical anesthesia	2	58.30	116.60
Ophthalmoscopy	1	1,340.00	1,340.00
Ocular tonometry	1	1,600.00	1,600.00
Eye irrigation	1	93.49	93.49
Visual acuity	1	1,600.00	1,600.00
Consumables (compress, solutions, etc.)			7.68
Total			4,944.75

RSD – Serbian dinars.

Table 2. Costs of services, medicines, medical devices, and consumables provided during the cataract surgery

Variable	ECCE		Phacoemulsification
	number of units	RSD	number of units	RSD
Services
peribulbar application of an anesthetic	1	1,800.00	1	1,800.00
surgery	1	38,284.19	1	38,284.19
subconjunctival application of medicine	1		1	1,340.00
sedation	1	2,810.00	1	2,810.00
in-patient day at general ward	1	1,545.40	1	1,545.40
in-patient day at semi-intensive unit	2	4,467.08	1	2,233.54
Medicines		574.63		553.33
Lens	1	682.00	1	3,626.70
Knifes	1	422.40	2	730.80
Other consumables		4,599.68		4,524.67
Total		55,185.37		55,185.37

ECCE – extracapsular cataract extraction; RSD – Serbian dinars.

Besides the two previously mentioned controls, the ECCE group of patients also included the costs for the third and fourth control after surgery necessary for patients operated by this method.

Table 2 shows the costs of medicines, materials, and services provided during the cataract surgery itself. Most consumables are the same; the most prominent differences were for the lenses used - soft with the phacoemulsification method, hard with the ECCE method, and consumables for the phacoemulsification machine. During phacoemulsification, two types of knives are used, while the ECCE method uses one kind of knife, but also surgical suture is necessary afterward. Furthermore, patients in the ECCE group have an additional day of hospitalization compared to the phacoemulsification group.

The capital cost was included in the phacoemulsification group since it represented a fixed expense incurred on the purchase of equipment used for surgery. That consisted of the cost of the phacoemulsification machine itself, machine consumables, service, and instruments, considering that 1,000 operations are performed annually. The price of the phacoemulsification machine was 4.13 million RSD, and it has depreciated over five years. The cost per patient is calculated by dividing the machine's price by the estimated number of operations over five years (5,000). The cost of machine consumables per patient is calculated in the same manner.

Moreover, the costs of complications are included in the analysis according to the administrative documentation for each patient with complications. The only exception was the cost of medicines used to treat corneal edema and macular edema, considering that the pharmacotherapy is applied at home.

Analysis

All calculations and analyses were performed using Microsoft Excel version 16 (Microsoft Corporation, USA, 2019). In cost-effectiveness analysis, results are presented as cost per patient without complications. An incremental costeffectiveness ratio (ICER) analysis was also performed. To assess the robustness of the model, a one-and two-way sensitivity analysis was performed. The following variables were tested in the sensitivity analysis: the annual number of operations with the phacoemulsification method and the effectiveness of the technique itself.

Results

The results of the cost-effectiveness analysis are shown in Table 3.

Table 3. Results of the cost-effectiveness analysis

Technique	Effect	D effect	Cost	D cost	ICER
ECCE	0.57		74,340.36
Phacoemulsification	0.87	0.30	71,008.70	- 3,331.66	Dominant (-11,105.53)

ECCE – extracapsular cataract extraction; ICER – incremental cost-effectiveness ratio; RSD – Serbian dinars.

Considering all the costs included in the study, the total cost per patient in the phacoemulsification group was 71,008.70 RSD, while the total cost in the ECCE group was 74,340.36 RSD. Considering the method's effectiveness regarding the percentage of patients without complications, phacoemulsification shows higher effectiveness (87%) than the ECCE method (57%). Due to these findings, costeffectiveness analysis shows that phacoemulsification is the dominant strategy compared to the ECCE method, meaning a technique with lower costs (-3,331.66 RSD) and higher effectiveness (0.3).

One-way sensitivity analyses were performed for an annual number of operations with the phacoemulsification method. The results were sensitive to this variable, where phacoemulsification stops being the dominant strategy if the number of operations drops below 350 per year. The two-way sensitivity analyses (number of operations and effectiveness of the phacoemulsification method) show that results were not sensitive to the effectiveness of the phacoemulsification method.

Discussion

According to the study results, phacoemulsification was more effective than the ECCE method due to a lower rate of complications (13% vs. 43%). That was similar to the Malaysian and Australian studies, with more common complications with the ECCE than the phacoemulsification technique [11][12].

On the side of the costs, the results of our study show lower costs associated with phacoemulsification as a possible method of cataract surgery. A combination of higher effectiveness and lower costs results in the dominant status of phacoemulsification. Additionally, according to the analysis, the result is sensitive to the number of operated patients per year. Results from our study are comparable with those from Kara-Junior et al. [13], which concluded a significant economic advantage in favor of the phacoemulsification technique, especially if the patient is working. A recent observational study from India showed similar results since phacoemulsification was found to be more cost-effective compared to other cataract techniques [14]. The study by Muralikrishnan et al. [15] estimated the cost of different cataract surgery procedures by applying various perspectives. Contrary to our results, the authors revealed that phacoemulsification is associated with the highest costs assuming the same perspective as in our study, due to the need for expensive equipment and consumables. Identical results were obtained in India, where phacoemulsification had higher provider direct costs (25.55 USD) compared with ECCE (16.25 USD), which were attributed to the cost of equipment and consumables [16].

The first published cost-effectiveness analysis revealed lower costs associated with ECCE compared to the phacoemulsification method in Australia [17]. The main reason for the difference in the results is that the authors assumed no difference between the two procedures based on expert opinion. Additionally, the authors concluded that any increase in the use of the phacoemulsification method results in decreasing costs, which is in line with our results.

Two studies conducted in Malaysia showed that the costs of phacoemulsification were higher than ECCE. A study from 2004 indicated no significant difference in costeffectiveness between the two methods [18], while a study from 2007 showed that ECCE is more cost-effective than phacoemulsification [8]. The difference with the results obtained in our study can be explained by the used unit of effectiveness. Namely, the studies used VA or vision-related quality of life evaluated by questionnaire.

The Cochrane Systematic Review from 2014 concluded that phacoemulsification results in better visual outcomes and a lower complication rate compared to ECCE. Still, the lower cost of ECCE may justify its use by maximizing the number of people that can be treated with restrained resources [19].

Evidence from different settings suggests that cataract surgery is cost-effective in developing countries and Western countries, with the range of results from cost-utility analysis from 9 USD to 25,000 USD per quality-adjusted life year [20][21][22][23]. Similar results were obtained using the other type of outcome, disability-adjusted life year [24].

The results of our analysis support the use of phacoemulsification as a dominant surgical method in General Hospital Kruševac. The study results from Poland also revealed phacoemulsification as the preferred surgical technique for cataracts [25].

Although the pharmacoeconomic evaluation was introduced more than one decade ago into the Serbian health care system, its influence is humble and rather advisory, especially in other health technologies besides medicines, such as surgical or diagnostic procedures.

This economic evaluation has some limitations. The sample for the study was taken retrospectively, and it reflects current clinical practice with a disproportional number of techniques. Moreover, the analysis did not include the time needed for the surgeon phacoemulsification training program since all surgeons included in the analysis are senior, experienced surgeons. The inclusion of this variable would alter the results and conclusion since published studies show a high learning curve [26]. The authors desired to perform a cost-utility analysis, but due to the unavailability of the patients, it was not possible to apply quality of life questionnaire to include humanistic outcomes in the study.

Conclusion

The phacoemulsification technique seems to be the preferred technique for cataract surgery based on the results of the pharmacoeconomic analysis. The study results justify the investment for phacoemulsification equipment and consumables if the number of surgeries per year in the health care institution is above 350. The phacoemulsification method in a healthcare institution is linked with clear economic and clinical outcomes, such as savings in monetary resources and a lower rate of complications.

Dodatak

Acknowledgment

This work was funded by a grant from the Ministry of Education, Science and Technological Development, Republic of Serbia (Project No. 451-03-9/2021-14/200161).