The epidemiology of funnel chest repairs in Germany: monitoring the success of Nuss’ procedure
The Cardiothoracic Surgeon volume 30, Article number: 17 (2022)
In recent years, the Nuss procedure was gaining ground in pectus excavatum repair, but the scientific focus had been on complications compared to conventional repairs. Despite a substantial prevalence of pectus excavatum in population-based studies, the adoption of minimally invasive funnel chest repair and subsequent replacement of conventional procedures has not been assessed on a population-based level.
We analysed German administrative case-based data on funnel chest repairs separate by age group and operative procedure: conventional or minimally invasive. Changes over time between 2010 and 2018 were analysed by linear regression.
There were x̅ = 256 operations per year, which did not change throughout the study time, but following the introduction of minimally invasive repairs, their usage increased particularly in males aged 15 to 19 years by 8.7 procedures per year (P = 0.0142) and was accompanied by a concomitant decrease in conventional repairs in all relevant age groups. We observed a shift of operations towards the age group of 15 to 19 years, whose numbers increased by 5.3 yearly procedures (P = 0.0222), whereas they decreased in all other relevant age groups. These shifts could not be observed in females in a similar fashion, but in both males and females, the numbers of minimally invasive per conventional repair increased.
In Germany, the introduction of the Nuss procedure did result in a concentration of funnel chest repairs in adolescence and a replacement of conventional repairs. Data from other healthcare systems are missing but are direly needed to assess the current situation in other healthcare systems.
Level of evidence
Much has been written about the “right” procedure for the repair of pectus excavatum since the introduction of the Nuss procedure . The main focus had been its complication rate in the analysis of the National Surgical Quality Improvement Program for both children  and adults , also in comparison with Ravitch repair . Although a considerable prevalence of pectus excavatum has been reported in population-based analyses [5, 6], similar data on the epidemiology of funnel chest repair is missing, particularly in adults. We aimed to address this issue by analysing the national hospital statistics of Germany with respect to pectus excavatum repairs in all age groups.
We obtained aggregated datasets from the Statistisches Bundesamt (Federal Statistics Office) including procedures of the German Modification of the International Classification of Diseases – version 10 for the years 2010 to 2018. The starting year was enforced by the data, because the Nuss procedure was not separately assessed before. We included all codes relevant for the repair of pectus excavatum: conventional repairs (OPS 5-346.a0), implantation of a subcutaneous prosthesis (OPS 5-346.a1), and Nuss procedures (OPS 5-346.a6). Population-based rates of repair were calculated by division of surgical procedures by the official population number on the reporting day of the Statistisches Bundesamt and provided in cases per 100,000 people. This was done separately for the age groups provided within the data. Detailed properties and pitfalls of these data have been discussed elsewhere . The administrative database is derived from hospital reimbursement statistics and covers cases, but not individual patients. Studies using administrative data are exempt from ethical approval, because the case-based data cannot be traced back to the individual patient .
Statistical analyses were conducted using R (RRID: SCR_001905) (version 3.5.3) with its generic stats4 package , if not stated otherwise. Changes over time were analysed by ordinary least squares linear regression [10,11,12,13], whose requirements of normality of residuals were checked by using the Kolmogorov-Smirnov test and the presence of homoscedasticity was verified by the Breusch-Pagan test, both from the olsrr package (version 0.5.3) , aided by visual analysis of QQ plots .
Since 2011, the number of conventional funnel chest repairs declined sharply in both males (Fig. 1A, C) and females (Fig. 1B, D), whereas the number of Nuss repairs rose in a similar fashion (Fig. 1F, G). In general, the operations of funnel chest repair with implantation of a subcutaneous prosthesis were rare in patients of both sexes (Fig. 1C, D). The total number of procedures did not change over time, but with an increasing fraction of minimally invasive procedures, the number of males operated on between 15 and 19 years of age rose by 5.3 procedures (F(1,6) = 9.364, P = 0.0222) per year in total. This was however just a shift towards an earlier operation during live, because the procedures in males between 20 and 24 years of age declined in a concomitant fashion by 5.1 yearly procedures (F(1,6) = 23.33, P = 0.0029).
Similar changes could not be observed in other age groups in both males and females. On a population-based level, this development did only alter the number of funnel chest repairs per 100,000 males aged 20 to 24 with − 0.2 (95% confidence interval − 0.3 to − 0.09) per year (F(1,6) = 20.42, P = 0.004) and for those in the age group between 25 and 29 years with − 0.06 (95% confidence interval − 0.11 to − 0.02) yearly procedures (F(1,6) = 11.47, P = 0.0147), whereas there were no changes in other age groups in males or in females at all (Fig. 2).
Among males in the age groups of 15 to 19 years, the number of Nuss’ procedures increased by 8.7 (95% confidence interval 2.5 to 14.9) per year (F(1,6) = 11.69, P = 0.0142) but did not change in the other age groups (Fig. 3A). This increase was accompanied by a concomitant decrease in conventional repairs in the age group between 10 and 14 years, in which the number of procedures decreased by 3.3 (95% confidence interval 4.9 to 1.7) per year (F(1,6) = 24.59, P = 0.0026) (Fig. 3B). Similar decreases could be found in those aged 15 to 19 years with 3.4 (95% confidence interval 5.7 to 1.1) yearly procedures (F(1,6) = 13.34, P = 0.0107), in those of age 20 to 24 with a similar decrease of 3.4 (95% confidence interval 5.4 to 1.4) procedures per year (F(1,6) = 17.14, P = 0.0061), and patients aged 25 to 29 years, in whom the number of conventional procedures decreased by 1.9 (95% confidence interval 3 to 0.8) per year (F(1,6) = 16.91, P = 0.0063) (Fig. 3B). For the remaining age groups in males, there were no differences in yearly procedures (Fig. 3B). In females, there has been no similar steep increase in the numbers of Nuss’ procedures in all age groups (Fig. 3C), but the data would be more compatible with a slight increase in the age groups between 15 to 19 and 20 to 24, although there is too much variability between the individual data points to clearly support this impression. Decreasing numbers of conventional procedures in females aged 10 to 14 years with 0.8 (95% confidence interval 1.5 to 0.1) per year (F(1,6) = 8.4, P = 0.0274) yearly procedures and a decrease of 0.4 (95% confidence interval 0.8 to 0.008) conventional procedures in females aged 25 to 29 years (F(1,6) = 6.237, P = 0.0467) also provide additional evidence for the aforementioned notion.
The substantial increase in minimally invasive funnel chest repairs could also be visualised by the number of Nuss procedures per conventional repair: They increased by 4.2 (95% confidence interval 0.6 to 7.7) per year in 10 to 14-year-old males (F(1,6) = 8.54, P = 0.0266), by 0.5 (95% confidence interval 0.08 to 0.97) in those aged 15 to 19 years (F(1,6) = 8.422, P = 0.0273), and by 0.5 (95% confidence interval 0.09 to 0.9) in males aged 20 to 24 years (F(1,6) = 9.155, P = 0.0232) but did not change in the other age groups in males (Fig. 4A). In females, this was only the case for those aged 25 to 29 years with a yearly increase of 1 (95% confidence interval 0.3 to 1.8) Nuss procedure per conventional repair (F(1,6) = 11.82, P = 0.0138). The data for the other age groups were also more compatible with an increasing relationship between minimally invasive and conventional funnel chest repairs but were too variable to model this increase by ordinary least square regression (Fig. 4B). This was heavily influenced by the small numbers of procedures in females (Fig. 1B, D, E), which made comparative modelling more difficult: For example, there were 18 Nuss procedures in 2018, but no conventional repair, which made the calculation of a ratio mathematically impossible, but highlights the wide adoption of the Nuss repair, although it could not be modelled by linear regression.
Despite a considerable prevalence of pectus excavatum in population-based analyses [5, 6], similarly, also population-based data on the epidemiology of funnel chest repair is missing. We aimed to fill this gap by analysis of the administrative, case-based German national hospital statistics, which has been described to be particularly useful to address such questions [15,16,17]. Using these data, we were able to describe a shift of procedures towards minimally invasive repairs, particularly in males, with a concomitant decrease in conventional procedures, but without an increase in overall procedures. Contrary to other procedures that have been investigated using this dataset [11, 13], in the present analysis, we are able to exclude that procedures have been missed due to their conduction on outpatients or even office-based, as this is impossible for funnel chest repairs.
Although the Nuss repair became much more frequent than conventional repairs in children aged 10 to 14 years, their numbers decreased and contributed towards the substantial increase in procedures in those aged 15 to 19 years. Although Nuss himself first developed his procedure in a 4-year-old boy , the median age at his centre has shifted from toddlers, as it was common with the open repair, to 14 years . While its inventors claimed that the minimally invasive procedure might be conducted at any age , supported by some centres , many others described technical modifications to be frequently necessary for the minimally invasive operation to be successful in adults [20,21,22], including surgeons that operate on children and adolescents, too . The marginal dissemination of such technical modifications might be a reason, why conventional repairs were still prevalent in Germany, particularly in adults aged 25 and older. On the other hand, techniques for open repair of pectus excavatum have enjoyed much popularity in Germany  and been advocated by influential surgeons of their periods such as Rehbein’s method , the Willital-Hegemann procedure , and the Erlangen method . We may thus not exclude that these factors played a role in the dissemination of the minimally invasive funnel chest repair.
We were able to demonstrate a shift towards minimally invasive repair of pectus excavatum in the last decade in Germany, although the total number of procedures did not change in the whole population. Nevertheless, population-based data on the epidemiology of funnel chest repair is missing and we hope to stimulate further research on this matter, particularly from other healthcare systems.
Availability of data and materials
The data that support the findings of this study are available from the Statistisches Bundesamt (German federal statistics office), but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission from the Statistisches Bundesamt (German federal statistics office).
Nuss D, Obermeyer RJ, Kelly RE (2016) Nuss bar procedure: past, present and future. Ann Cardiothorac Surg 5:422–433
Tetteh O, Rhee DS, Boss E, Alaish SM, Garcia AV (2018) Minimally invasive repair of pectus excavatum: analysis of the NSQIP database and the use of thoracoscopy. J Pediatr Surg 53:1230–1233
Brungardt JG, Chizek PW, Schropp KP (2021) Adult pectus excavatum repair: national outcomes of the Nuss and Ravitch procedures. J Thorac Dis 13:1396–1402
Jawitz OK, Raman V, Thibault D, Yerokun B, Zwischenberger BA, Kosinski AS et al (2021) Complications after Ravitch versus Nuss repair of pectus excavatum: a Society of Thoracic Surgeons (STS) General Thoracic Surgery Database analysis. Surgery. 169:1493–1499
Westphal FL, Lima LCD, Lima Neto JC, Chaves AR, Santos Júnior VL, dos, Ferreira BLC. (2009) Prevalência de pectus carinatum e pectus excavatum em escolares de Manaus. J Bras Pneumol 35:221–226
Biavati M, Kozlitina J, Alder AC, Foglia R, McColl RW, Peshock RM et al (2020) Prevalence of pectus excavatum in an adult population-based cohort estimated from radiographic indices of chest wall shape. PLoS One 15:e0232575
Nimptsch U, Spoden M, Mansky T (2020) Variablendefinition in fallbezogenen Krankenhausabrechnungsdaten – Fallstricke und Lösungsmöglichkeiten. Gesundheitswesen. 82(S 01):S29–S40
Doppelfeld E, Hasford J (2019) Medizinische Ethikkommissionen in der Bundesrepublik Deutschland: Entstehung und Einbindung in die medizinische Forschung. Bundesgesundheitsbl. 62:682–689
R Core Team. R (2019) a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna
Heydweiller A, Kurz R, Schröder A, Oetzmann von Sochaczewski C (2021) Inguinal hernia repair in inpatient children: a nationwide analysis of German administrative data. BMC Surg 21:372
Oetzmann von Sochaczewski C, Gödeke J, Muensterer OJ (2021) Circumcision and its alternatives in Germany: an analysis of nationwide hospital routine data. BMC Urol 21:34
Oetzmann von Sochaczewski C, Muensterer OJ (2021) The incidence of infantile hypertrophic pyloric stenosis nearly halved from 2005 to 2017: analysis of German administrative data. Pediatr Surg Int 37:579–585
Oetzmann von Sochaczewski C, Muensterer OJ (2021) Laparoscopy for abdominal testes: nationwide analysis of German routine data. J Laparoendosc Adv Surg Tech A 31:236–241
Hebbali A (2020) olsrr: tools for building OLS regression models
Oetzmann von Sochaczewski C, Gödeke J (2021) Pilonidal sinus disease on the rise: a one-third incidence increase in inpatients in 13 years with substantial regional variation in Germany. Int J Colorectal Dis 36:2135–2145
Schieferbein V, Windfuhr JP (2021) Häufigkeit sekundärer Tonsillektomien in Deutschland. HNO. 69:886–890
Nimptsch U, Haist T, Gockel I, Mansky T, Lorenz D (2019) Complex gastric surgery in Germany—is centralization beneficial? Observational study using national hospital discharge data. Langenbecks Arch Surg 404:93–101
Kelly RE, Goretsky MJ, Obermeyer R, Kuhn MA, Redlinger R, Haney TS et al (2010) Twenty-one years of experience with minimally invasive repair of pectus excavatum by the Nuss procedure in 1215 patients. Ann Surg 252:1072–1081
Hoksch B, Kocher G, Vollmar P, Praz F, Schmid RA (2016) Nuss procedure for pectus excavatum in adults: long-term results in a prospective observational study. Eur J Cardiothorac Surg 50:934–939
Jaroszewski DE, Ewais MM, Chao C-J, Gotway MB, Lackey JJ, Myers KM et al (2016) Success of minimally invasive pectus excavatum procedures (modified Nuss) in adult patients (≥ 30 years). Ann Thorac Surg 102:993–1003
Lo P-C, Tzeng I-S, Hsieh M-S, Yang M-C, Wei B-C, Cheng Y-L (2020) The Nuss procedure for pectus excavatum: an effective and safe approach using bilateral thoracoscopy and a selective approach to use multiple bars in 296 adolescent and adult patients. PLoS One 15:e0233547
Uemura S, Yoshida A, Kuyama H (2021) Rib osteotomy with the Nuss procedure for the repair of adult pectus excavatum. Gen Thorac Cardiovasc Surg 69:409–411
Rokitansky AM, Stanek R (2012) Modified minimally invasive pectus repair in children, adolescents and adults: an analysis of 262 patients. Eur Surg 44:222–231
Schulz-Drost S, Syed J, Luber A-M, Carbon RT, Besendörfer M (2019) From pullout-techniques to modular elastic stable chest repair: the evolution of an open technique in the correction of pectus excavatum. J Thorac Dis 11:2846–2860
Rehbein F, Wernicke H-H (1957) The operative treatment of the funnel chest. Arch Dis Child 32:5–8
Saxena AK, Schaarschmidt K, Schleef J, Morcate JJ, Willital GH (1999) Surgical correction of pectus excavatum: the Münster experience. Langenbecks Arch Surg 384:187–193
Weber P, Hümmer H (2006) Die “neue” Erlanger Trichterbrustkorrektur - Minimalisierung eines bewährten Verfahrens. Zentralbl Chir 131:493–498
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Ethics approval and consent to participate
Strictly anonymous aggregated data such as the German national hospital statistics are exempt from ethical approval . As such, no regulatory body may be able to grant ethical approval for something that is approved by the law itself. The owner of the data—the Statistisches Bundesamt (German federal statistics office)—licensed the data to the authors and did thereby authorise them to use and analyse the strictly anonymous data.
Consent for publication
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Heydweiller, A., Oetzmann von Sochaczewski, C. The epidemiology of funnel chest repairs in Germany: monitoring the success of Nuss’ procedure. Cardiothorac Surg 30, 17 (2022). https://doi.org/10.1186/s43057-022-00079-2