Background
Strabismus is a common eye disease, with a prevalence of 1–4% in the population [
1‐
3]. Many factors affect the prevalence of strabismus, such as age, gender, region, refraction, etc. There are different views on the trend of strabismus prevalence with age. Kvarnström et al. [
4] considered that age is an important factor of the prevalence of strabismus. However, some studies have shown that age does not affect the prevalence of strabismus [
5,
6]. Refractive error is also one of the important factors influencing the prevalence of strabismus. The prevalence of strabismus in western countries is higher than that in Asian countries [
7], probably because of the high incidence of hyperopia [
8,
9]. In addition, the higher prevalence of strabismus in female may be related to the higher prevalence of hyperopia in female [
10]. However, some studies suggest that there is no gender difference in the prevalence of strabismus [
11,
12]. Gender differences may be due to other factors, such as age distribution, race, and genetic and environmental factors of the study population [
7]. It has been reported that the prevalence of strabismus has no significant correlation with age, gender, place of residence and refractive error [
13]. The risk factors of strabismus include premature birth, low birth weight, smoking during pregnancy, family history, etc. [
12,
14,
15].
The effects of strabismus are multidimensional, with potentially detrimental effects on overall health and quality of life [
1,
3,
16‐
20]. Even the quality of life of the family members of strabismus patients may decline [
21,
22]. Most types of strabismus usually require surgical treatment, and studies have demonstrated the clinical and functional benefits of strabismus surgery [
20,
23‐
26]. It can improve binocular vision and psychosocial functioning. Even in adults with long-standing strabismus, binocular vision improves after strabismus surgery, and stereopsis may be restored in some patients [
24,
27]. However, strabismus surgery is often labeled as “cosmetic”, that is the reason why strabismus is not in health insurance coverage in China, and even many ophthalmologists hold the same misconception [
28].This prevents strabismus patients from getting treatment in early stages.
Accurate estimates of strabismus treatment costs are necessary for health care. Information on hospitalization costs associated with strabismus surgery is equally important for clinicians to increase their understanding of the economic impact of surgical interventions, as well as for patients to get information of the accurate manner of expected medical costs. Previous studies have mostly paid attention to assess the cost utility and functional and psychosocial benefits of strabismus surgery [
29‐
32], but the year-to-year trends in hospitalization costs for strabismus and the associated influencing factors have not been systematically studied. The purpose of this study was to present a 6 -year trend and influencing factor analysis of the overall hospitalization costs associated with strabismus surgery.
Methods
Data source and sample size
The data were obtained from the information system database of the eye hospital of the first affiliated hospital of Harbin medical university. The eye hospital is the best eye hospital in Northeast China. Information on the inpatient medical expenses of all strabismus patients from January 2014 to July 2019 was extracted from the database, with a total of 3819 strabismus patients.
Medical expenditure data inclusion/exclusion criteria
The inclusion of medical expenditure data for hospitalized patients is subject to the following conditions simultaneously: (1) a diagnosis of strabismus requiring surgery; (2) a single diagnosis with no other medical treatment costs incurred; (3) the discharge date is From January 1st, 2014 to July 31st, 2019; (4) the patient’s basic information, cost information, and clinical information (clinical diagnosis, treatment plan, anesthesia, etc.) are complete.
Exclusion criteria: (1) cases with two or more diseases; (2) patients with incomplete information.
A total of 3819 inpatients with strabismus from 2014 to 2019 year were extracted from the database. 31 cases with incomplete information and 192 cases with non-single diagnosis were excluded, finally 3596 cases of strabismus being included in this study.
Categories of medical expenses for this study: surgical treatment (surgery, anaesthesia), drug, medical consumables (consumables for treatment, consumables for surgery), examinations (laboratory test, imaging and clinical diagnostic items), others (general medical service, general treatment operation, nursing and other).
Data analysis
All costs are reported in China Yuan (CNY) based on the value in 2014, and are calculated based on the Consumer Price Index (CPI) for urban residents in Heilongjiang Province, with price adjustments for yearly medical expenses. Statistical analysis was performed using SAS 9.4 and SPSS 24.0 software. To analyze the changes of various expenses in different years: (1) to calculate the mean and standard deviation of costs for each year; (2) the cost was used as the dependent variable, the CPI as the covariate, and the year was included in the linear regression model as a continuous variable, and the P value of the linear trend test of the cost change with the year was obtained; (3) the cost was used as the dependent variable, the CPI as the covariate, and the year was included in the regression model as a categorical variable (2014 as the reference level), and covariance analysis was performed. Partial correlation was used to analyze the relationship between the total cost and sub-cost for each year, adjusting the CPI, and calculating the Spearman’s correlation coefficient. Nonparametric tests and univariate linear regression were used to analyze the relationship between total cost and gender, funding, age, length of hospital stay. On the basis of univariate analysis, multiple linear regression was used to analyze the influence of each factor on the total cost.
Values of P < 0.05 were considered statistically significant.
Discussion
Strabismus surgery has been shown to be cost-effective and “very cost-effective” [
31,
32], with similar health benefits to cataracts [
31]. This is the first comprehensive study to reflect the current situation of medical costs associated with strabismus surgery by analyzing the trend of strabismus surgery costs and its influencing factors.
In this study, the number of patients under the age of 12 still accounts for the largest proportion, about 48.4%. It is probably traceable to the increasing attention to children’s health, increasing consultation and screening rates of children as higher living standards in China [
33]. Most children receive treatment in the early stages of the disease. Kvarnström et al. pointed out that the prevalence of strabismus was highest in 4 -year-old children, and then showed a downward trend [
8]. This shows that strabismus is still a common disease in children [
34]. In terms of funding, over 80% of the patients in this study paid fees themselves. All types of strabismus have not been included in the scope of medical insurance reimbursement except paralytic strabismus in China. As we know, the main purpose of strabismus treatment is to improve the binocular visual function and psychosocial function [
35,
36]. Strabismus surgery not only is a cosmetic procedure, but also is a functional restoration procedure [
29]. Therefore, it is recommended that strabismus should be brought into the scope of medical insurance in China. Medical insurance can supervise medical services, guide medical institutions to take the initiative to control costs and provide early treatment to more patients, especially those with a heavier financial burden [
37]. The early diagnosis and treatment of strabismus are essential to restore visual function and reduce the risk of amblyopia [
38].
This study found that the total cost of hospitalization for strabismus increased over time. The year-on-year growth rate of hospitalization expenses in 2017 and 2018 was significantly higher than those in 2015 and 2016. The most of the sub-costs kept increasing, especially the costs of consumables and examinations, which leading to a significant increase in the total hospitalization costs. The only sub-costs that have declined were the costs of drug (particularly Western medicine) and general medical service, which may be influenced by the zero-mark-up medicines policy that has been fully implemented in the hospital since 2017. In China, a series of policies about the zero-mark-up medicines is the part of the new health-care reform, including abolition of drug mark-ups in all public hospitals, reduction of the prices of medical consumables and examination, raising the prices of items that reflect the value of the technical services of medical staff, such as surgery, nursing, etc. [
39]. The general goal of the reforms were the growth rate of medical expenses in public hospitals reduced to less than 10% [
39]. The hospital fell short of its goal, from the data of the study. There are many possible reasons: (1) the relatively slow increase in the cost of medical items reflecting the professional value, and the rapid reduction for drug costs (surgery costs showed a negative increase in 2018, while drug costs fell at a maximum rate of 22.5%).Those led to excessive examinations, and the total costs did not decrease but increase [
40,
41]. (2) The price and amount of consumables used are not clearly specified, which may lead to high consumables costs and frequent use of consumables [
42]. (3) Strabismus is not included in the medical insurance coverage, so medical insurance policy cannot be used to restrain medical behavior.
The cost of surgical treatment showed a downward trend except for a slight increase in 2017. The proportion of examinations costs and consumables costs have increased year by year, which was unreasonable and resulted in the continuous increase of the total cost of hospitalization.
The study shows the main factors, which influence the total of hospitalization for strabismus, are consumables costs, type of anesthesia and age. Consumables costs had a greater impact on the change of hospitalization costs. Therefore, it is necessary to reduce consumables costs and examinations costs, and to increase the costs for medical services, such as nursing costs, treatment costs and operation costs, etc. [
43]. In particular, it is necessary to increase the cost of surgery reasonably. Compared with cataract, strabismus surgery was performed by two doctors. So operation costs should be more higher [
29], in order to reflect the labour value of the medical staff.
The different anaesthesia techniques affect the total cost of hospitalization and the proportion of each sub-costs. The cost of general anaesthesia is significantly higher than that of local anaesthesia. General anaesthesia is often used for strabismus surgery in some countries and regions [
29]. However, we believe that topical anaesthesia combined with local infiltration should be used as far as possible when the patients can cooperate and tolerate the procedure. There are three possible explanations. The first, topical anaesthesia can avoid the risks of general anaesthesia and other local anaesthetic techniques [
44], reduce the incidence of oculocentric reflexes [
45], post-operative nausea and vomiting [
46,
47], and recover faster for post-operative patients. In addition, with the cooperation of the patients during the operation, the strabismus surgery with one-stage adjustable sutures can bring better effect and long-term stability [
48,
49]. At last, it can reduce the total cost of hospitalization for strabismus and the economic burden of patients.
The multivariate analysis showed that the younger the age, the higher the cost of hospitalization. Patients with strabismus at different ages may have an impact on the total cost of hospitalization in various ways. The proportion of patients (≤ 12 years old) under general anaesthesia is over 90%In addition, the costs of items, such as blood collection and nursing are charged at an additional 20–30% for children(≤ 6 years old).
The optimal timing of strabismus surgery is still controversial, but it is widely accepted that strabismus surgery should be performed before children’s visual maturity (before 8 years old) [
50]. Although the younger the child is, the greater the cost of strabismus surgery, from the perspective of patients early surgery can improve visual function without adverse long-term effects.
Age and the mode of anesthesia interact to some extent and work together on the total hospital costs. For example, 12-year-old strabismus patients mostly use general anesthesia (> 90%), with the average hospitalization cost of 6343.4 CNY. In addition, the proportion of general anesthesia in patients aged 13–24 years was about 42.6%, with the average hospitalization cost of 5352.8 CNY.
In this study, the length of stay did not have a statistically significant effect on hospitalization costs. However, previous studies have shown that the length of stay of many diseases heavily influenced hospitalization costs [
51‐
53]. This may be due to the fact that the majority of strabismus patients are children with no other concomitant illnesses which incur additional costs. In addition, post-operative examination cannot be required for strabismus during hospitalization and only items with lower fees were charged, such as consultation and nursing fees. Besides, the short duration of strabismus surgery and the absence of serious post-operative complications make it suitable for day ward management. The day ward shortens the length of stay, reduces the stress, anxiety and mental strain caused by prolonged hospitalization, and improves patient satisfaction. The shorter length of hospital stay also speeds up bed turnover, freeing up more beds for critically ill patients and greatly improving bed utilization efficiency [
54].
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