Population-based analysis of the epidemiology of the surgical correction of hyperhidrosis in 1,216 patients over 11 years: a cross-sectional study

Abstract BACKGROUND: Endoscopic thoracic sympathectomy is the definitive surgical treatment for hyperhidrosis and a nationwide study has suggested that cultural and socioeconomic factors play a role in the numbers of operations performed. Thus, there is a need to evaluate local data in order to understand the local epidemiology and trends in hyperhidrosis treatment. OBJECTIVE: To study the epidemiology of sympathectomy for treating hyperhidrosis in São Paulo, the largest city in Brazil. DESIGN AND SETTING: Population-based retrospective cross-sectional study. METHODS: Data on sympathectomies for treating hyperhidrosis between 2008 and 2018 were assessed from the database of the Municipal Health Department of São Paulo, Brazil. RESULTS: 65.29% of the patients were female, 66.2% were aged between 20 and 39 years and 37.59% had registered with addresses outside São Paulo. 1,216 procedures were performed in the city of São Paulo from 2008 to 2018, and 78.45% of them were in only two public hospitals. The number of procedures significantly declined over the years (P = 0.001). 71.63% of the procedures were associated with 2-3 days of hospital stay, only 78 intensive care unit days were billed and we did not observe any intra-hospital death. CONCLUSION: The profile of patients operated on in São Paulo (young women) is similar to that described in other populations. Sympathectomy is a very safe procedure, with no mortality in our series. There was a decreasing trend in the number of surgeries over the years.


OBJECTIVE
To study the epidemiology and outcomes of ETS for treating HH in the city of São Paulo, with evaluation of the total number of ETS performed for treating HH, hospital volumes, trends over time, costs, in-hospital mortality and lengths of hospital and intensive care unit (ICU) stay, along with the proportion of patients from other cities who came to São Paulo to undergo ETS for treating HH. For statistical analysis, linear regression analysis was performed to evaluate the trends in procedures over the years, using the SPSS version 22.0 (IBM Corp. Armonk, New York, United States). For all tests, the level of statistical significance was taken to be α = 0.05. This study was approved by the ethics committee of the institution where it was conducted (procedural number 3067-17; approved on July 18, 2017). Data are anonymous at DATASUS; therefore a waiver of informed consent was requested and granted by our institutional review board.

RESULTS
Most of the patients were female (65.29%), aged between 20 and 39 years (66.2%) and with a registered residential address in the city of São Paulo (62.41%). The age stratification of the operated patients is presented in Table 1. The number of procedures, equivalent dollar amounts reimbursed by SUS and average amounts per procedure according to hospital establishment are presented in Table 3.

Patients' demographics
In line with previous reports, we observed a predominance of female patients. 1,8 Even though the prevalence of HH is similar between the sexes, 5 there is a greater demand for treatment among females, likely due to generally greater esthetic concern in this group. [12][13][14][15] Regarding age, ETS for treating HH has proven to be beneficial for a wide range of age groups. 16,17 However, the demand for treatment of hyperhidrosis is estimated to be greater in young and economically active age groups, 5 which is in agreement with our findings, as most individuals in our study were aged between 20 and 39 years (66.2%).
More than one third of the patients had registered with addresses outside of the city of São Paulo (37.59%). Healthcare inequalities in Brazil and the concentration of resources in its southeastern region, and in some southeastern centers like the city of São Paulo, are well documented. 9 A similar high proportion of out-of-town patients who come to the city of São Paulo to seek treatment has been observed in other reports. 18 The state of São Paulo comprises 645 municipalities, which are organized into 17 healthcare service reference regions (HSRR). 19 Ideally, in accordance with the principle of regionalization of the Brazilian National Health System, each HSRR should be designed to meet most of the healthcare demands of its municipalities. 20 The city of São Paulo is the only municipality included in its HSRR. 19 Hence, the patients treated by mean of sympathectomy for hyperhidrosis  Hospital  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  1  153  158  81  65  32  94  45  36  34  31  24  2  3  0  17  12  20  34  42  53  3  10  7  3  28  9  13  10  3  12  0  0  0  0  1  4  2  0  0  0  11  7  9  7  3  16  11  5  2  7  3  10  18  7  5  0  3  1  0  6  3  3  2      with a registered address outside of the city of São Paulo, belonged to other HSRRs. 19 It is likely that many of these patients went to São Paulo to seek treatment, thus practicing healthcare tourism,

Procedure rates and trends
Starting in the first year of the period studied, we observed a progressively downward trend in the number of ETS procedures for treating HH. This contrasts with national statistics showing an initial upward trend between 2008 and 2012, and a downward trend thereafter. 8 This difference may have been because the municipal center with the highest volume of ETS (hospital 1) was also the one in which an "oxybutynin first" protocol for treating HH started to be used in 2007, such that sympathectomy was then reserved for refractory cases or for patients with intolerance to oral treatment, in an attempt to reduce the incidence of compensatory hyperhidrosis, a common complication after sympathectomy. [21][22][23][24] Good results from the "oxybutynin first" strategy started to be reported from 2011 onwards, 25-31 which might well have contributed to the national decrease in use of ETS for treating HH from 2012 onwards.

Hospital and ICU length of stay and in-hospital mortality
We observed that the hospital stay was short, in line with other studies. 32,33 Most of the patients were discharged on the second or third day of hospitalization, which likely corresponded to the first and second postoperative days, respectively, given that patients are usually admitted on the day before the surgery.
Regarding ICU length of stay, due to the anonymity of the data, we only had access to the total number of ICU days paid by the government. Thus, we did not know how many patients were admitted to the ICU and for how many days, or what the indications for ICU admittance were. These therefore were limitations of our study. In total, we observed that 78 days of ICU stay were reimbursed to the hospitals, which were unevenly distributed over

Costs
A total of 534,916.96 USD was reimbursed by the government for ETS for treating HH, with an average amount of 439.90 USD per procedure, a little less than reported by other authors. 35 One of the limitations of our cost analysis was that the reimbursement was based on a compensation table for procedures, which often does not reflect the actual amount spent on procedures by the hospitals. We may conjecture that the decrease in the number of surgeries may have led to higher public expenditure on clinical treatments. As HH is a frequent disease among young people, who may use medications over the long term, this should be considered within publicly funded healthcare, although a cost-effectiveness study would be necessary in order to evaluate it properly.

Limitations
Besides the limitations already mentioned, i.e. anonymous data precluding follow-up and adjusted analysis, along with reimbursement based on a fixed compensation table, another limitation of our study was that the database only provides data relating to selected procedures performed in accredited public hospitals.
Thus, the database is susceptible to some loss of data.
On the other hand, this was a comprehensive and detailed epidemiological analysis on sympathectomy for treating HH that made use of objective data that had been compulsorily recorded in a public database. Our findings revealed the demographics of patients who were seeking surgical treatment for hyperhidrosis and the high volume of out-of-town patients who were seeking treatment in São Paulo; and highlight the safety of this treatment.

CONCLUSIONS
Over the last 11 years, sympathectomy for treating HH has been widely performed in the city of São Paulo. The profile of patients operated on in São Paulo (young women) is similar to that described in other populations. Sympathectomy is a very safe procedure, with no mortality in our series. There was a decreasing trend in the number of surgeries over the years.