A systematic review on the association between body mass index and autologous breast reconstruction
Review Article

A systematic review on the association between body mass index and autologous breast reconstruction

Nicolai Lassen Frid, Elisabeth Lauritzen, Tine Engberg Damsgaard

Department of Plastic Surgery and Burns Treatment, Rigshospitalet and Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark

Contributions: (I) Conception and design: NL Frid, TE Damsgaard; (II) Administrative support: NL Frid, TE Damsgaard; (III) Provision of study materials or patients: All authors; (IV) Collection and assembly of data: NL Frid; (V) Data analysis and interpretation: NL Frid; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

Correspondence to: Nicolai Lassen Frid, MD. Department of Plastic Surgery and Burns Treatment, Rigshospitalet and Institute of Clinical Medicine, University of Copenhagen, Inge Lehmanns Vej 8, 2100 Copenhagen, Denmark. Email: Nicolai.Lassen.Frid.01@regionh.dk.

Background: The incidence of breast cancer is increasing, and the prevalence of obesity is rising. The aim of the study was to investigate the association between body mass index (BMI, kg/m2) and postoperative complications at the recipient site among women who have had autologous breast reconstruction based on free abdominal flaps. Furthermore, the aim is to investigate whether there is a BMI threshold where autologous breast reconstruction may not be recommended.

Methods: Medline/PubMed and EMBASE via OVID were searched using relevant terms. The literature was assessed using the PRISMA guideline. All studies reporting recipient site complications after autologous breast reconstruction, using either deep inferior epigastric artery perforator flap, superficial inferior epigastric artery flap, muscle-sparing or free transverse rectus abdominis musculocutaneous (TRAM) flap were included. BMI was stratified according to World Health Organization (WHO) classification and furthermore defined as obese (BMI ³30 kg/m2) and non-obese (BMI <30 kg/m2). Data regarding postoperative outcomes were combined for pooled analyses. Strengthening the reporting of observational studies in epidemiology (STROBE) statement was used for a combined quality and bias assessment.

Results: Twenty studies met the inclusion criteria, encompassing a total of 10,514 patients and 11,458 flaps. Pooled analyses showed significant increased minor- and major complication rates and loss of reconstruction when compared the obese to the non-obese group. Stratifying BMI according to WHO criteria revealed significantly higher odds ratio (OR) for minor complications for all groups of obesity when compared to the normal weight group. The risk of loss of reconstruction was significantly higher in the class III obese group when compared to the normal weight.

Conclusions: In the autologous breast reconstructive population, obese patients (BMI ³30 kg/m2) have an increased risk of both minor- and major complications, as well as loss of reconstruction when compared to the non-obese population (BMI <30 kg/m2). Stratifying levels of obesity according to WHO’s BMI criteria shows increased OR for minor complications in all groups. However, autologous breast reconstruction may still be a viable option for this population. This study may be limited due to the heterogeneity of the included flaps and the quality of the included studies.

Keywords: Breast reconstruction; body mass index (BMI); postoperative complications; autologous breast reconstruction

Received: 21 June 2023; Accepted: 13 October 2023; Published online: 03 November 2023.

doi: 10.21037/abs-23-46

Highlight box

Key findings

• In the autologous breast reconstructive population, obese patients [body mass index (BMI) ≥30 kg/m2] have an increased risk of both minor and major complications, as well as loss of reconstruction when compared to the non-obese population (BMI <30 kg/m2).

• Stratifying levels of obesity according to World Health Organization (WHO)’s BMI criteria shows increased odds ratio for minor complications in all groups. Loss of reconstruction is drastically increased when BMI ≥40 kg/m2.

What is known and what is new?

• Obesity is associated with increased complication rates.

• Despite the increased risk of minor complication in the obese groups, autologous breast reconstruction may still be a valid option for the obese population in selected cases.

What is the implication, and what should change now?

• Considering the high rates of complications among patients with a BMI exceeding 30 kg/m2 who undergo breast reconstruction, it is advisable to provide thorough counselling about the risks and possible delay in reconstruction until weight loss has been achieved.

Introduction

Breast cancer (BC) is the most common type of cancer in women worldwide (1,2). The incidence of BC is increasing in both the developed and the developing world (1,2). Furthermore, the prevalence of obesity is rising, which has been shown to have a negative prognostic impact on BC in women. Obesity is also a known risk factor for developing BC among postmenopausal women (3-8). Obesity increases the risk of venous thromboembolism and the obese population has a greater risk for surgical site infection and slower healing because of the reduced blood flow in fat tissue (9-12).

The treatment of BC has the highest priority. Due to significant improvement in diagnosis and surgical-, medical- and therapeutic treatment, BC is no longer the main cause of cancer death in Europe (2,13). Surgical intervention is the primary regional and local treatment, with breast conserving surgery (BCS), sentinel lymph node biopsy (SLNB) and mastectomy as some of the treatment modalities (14,15).

Body mass index (BMI) is one of the simplest measures for screening for obesity. It is limited due to the lack of distinguishing between excess body fat, muscle or bone mass, and not including factors such as sex and ethnicity. Compared to more precise ways to calculate body fat, as dual energy X-ray (DEXA) and magnetic resonance imaging (MRI), BMI has its advantages regarding cost efficiency, accessibility and internationally usage as initial screening of overweight and obesity for adults (16,17).

Decision to perform mastectomy depends on tumor and breast size, recurrence of tumor, presence of Breast Cancer (BRCA) gene mutation and type of carcinoma. In addition to the psychological and emotional distress the patient experiences, women undergoing mastectomy may also suffer psychosocial distress due to body image distortions.

Trends in a nationwide study in the United States, show rates of breast reconstruction in women undergoing mastectomy have increased from 11.6% in 1998 to 36.4% in 2011 (18). In Europe however, trends show lower rates of both immediate and delayed breast reconstruction in comparison to the total number of mastectomies, and a decrease in mastectomy rates (19,20). The advances in the surgical management of BC has led to a growing preference for a more conservative approach (21).

Health-related quality of life (HRQOL) outcomes comparing patients undergoing either mastectomy or mastectomy and immediate breast reconstruction, shows improved physical and social outcomes in the breast reconstructive group (22-25). Immediate and delayed breast reconstruction have shown improvements in both body image and sexual well-being, therefore alleviating some of the psychosocial challenges related to diagnosis and treatment (26,27).

Improvements in surgical techniques and the development of the free microvascular tissue flap have resulted in more advanced and complex reconstructive options (28). The addition of autologous breast reconstruction to tissue expander/implant-based/acellular matrix-assisted procedures, have provided the patient with a multitude of options for a more natural reconstruction in terms of shape, size and symmetry of the breast. Abdominal based autologous breast reconstruction includes; the pedicled or free transverse rectus abdominis musculocutaneous (TRAM) flap, muscle-sparing TRAM (msTRAM) flap, the free deep inferior epigastric perforator (DIEP) flap and the superficial inferior epigastric artery (SIEA) flap. BMI (kg/m2) is among several important factors when planning surgery and in deciding the most suitable breast reconstruction for the individual patient.

This study aims to investigate the association between BMI and postoperative complications at the recipient site (i.e., the breast) among women undergoing autologous breast reconstruction with free abdominal-based flaps.

Immediate- and delayed breast reconstruction with TRAM, msTRAM, DIEP and SIEA flaps were reviewed. BMI were stratified by World Health Organization (WHO) classification investigating any statistical differences in complication rates among the BMI categories.

Based on complication rates, we sought to investigate if a possible BMI threshold for not recommending autologous breast reconstruction in the obese population.

Furthermore, the aim is to investigate differences between the obese and non-obese patients with respect to recipient site complications. We present this article in accordance with the PRISMA reporting checklist (29) (available at https://abs.amegroups.com/article/view/10.21037/abs-23-46/rc).

Methods

Search strategy

Adhering to the PRISMA guidelines, a systematic search of Medline via PubMed and EMBASE via OVID were performed in December 2020 and updated in September 2022. Databases were searched using the following keywords: “BMI” OR “Body Mass Index” AND “Mammaplast” OR “Breast reconstruction” OR “Autologous breast reconstruction” AND “DIEP” OR “Deep inferior epigastric perforator” OR “SIEA” OR “Superficial inferior epigastric artery” OR “TRAM” OR “Transverse rectus abdominis musculocutaneous” OR “Flap” OR “Surgical flaps” AND “Complication” OR “Postoperative” OR “Post operative” OR “Post operative complications” OR “Outcome” OR “Treatment outcome”.

“Body Mass Index”, “Mammaplasty”, “Surgical flaps” and “treatment outcome” were used as Medical Subject Headings (MeSH) terms at the PubMed database.

Inclusion and exclusion criteria

All studies, without date limitation, reporting recipient site complications after autologous breast reconstruction, using free abdominal flaps, either DIEP, msTRAM, TRAM and SIEA flaps and evaluating outcomes based on BMI were included.

Studies not specifying type of autologous breast reconstruction and/or if outcomes were only reported on donor-site were excluded (30). Also, studies not stratifying BMI according to WHO criteria or pairing in a BMI <30 and ³30 kg/m2 group were excluded (31,32).

BMI stratification was defined according to WHO classification; normal weight (BMI 18.5–24.9 kg/m2), overweight (BMI 25–29.9 kg/m2), class I obese (BMI 30–34.9 kg/m2), class II obese (BMI 35–39.9 kg/m2) and class III obese (BMI ³40 kg/m2). Furthermore, as obese (BMI ³30 kg/m2) and non-obese (BMI <30 kg/m2) (33,34).

Outcome measures

The primary outcome measures were grouped as ‘minor complications’, ‘major complications’ and ‘loss of reconstruction’. Minor complications were classified as complications treated conservatively, and not requiring any surgical intervention. Major complications were defined as complications requiring surgical intervention in local or general anesthesia as well as loss of reconstruction. Loss of reconstruction was defined as the number of total flap failures.

In addition, patient demographics, timing of reconstructive procedure (immediate or delayed), staging, and follow-up periods were recorded.

Hematoma, partial flap loss, mastectomy skin loss (wound edge necrosis, marginal necrosis, mastectomy flap necrosis), thrombosis, revision, re-exploration and microsurgical were categorized as major complications.

If a study did not specify treatment of complications, and were not suitable for the definition of major complications, they were categorized as minor complications.

Study selection and data extraction

One thousand one hundred and ninety-four studies were retrieved with 756 articles left after removing duplicates. Six hundred and seventeen were excluded after screening title and abstract, 119 papers were excluded after full text readthrough, leaving 20 studies to be included for analyses (Figure 1).

Figure 1 PRISMA flow chart. BMI, body mass index.

Data were extracted from the included studies according to BMI and predefined outcome measures. The authors agreed on the data extracted.

Statistical analysis

Statistical analysis was performed using R version 1.2.5033 and Microsoft Excel 2010 version 16.40. Data were combined for pooled analysis. Data were both extracted as complication per breast and per woman. If a study did not report 1 of the 3 outcomes, it was excluded from the subgroup analysis. Categorical variables were summarized and compared using Pearson’s Chi-squared and Fisher’s exact tests. Statistical significance was set at a P value of <0.05.

Risk of bias in individual studies and level of evidence

Strengthening the reporting of observational studies in epidemiology (STROBE) statement was used for a combined quality and bias assessment of all included observational studies (35). The individual studies were assessed by the author within each domain and classified as sufficient (+) or insufficient (−). Based on the individual judgments, each study was given an overall risk of bias: low risk, moderate risk or serious risk.

Each of the included papers were rated according to the American Society of Plastic Surgeons (ASPS) Levels of Evidence Scale (36). The higher the level, the more reliable results and the more valid conclusions to be drawn from the paper.

Results

Study characteristics

Twenty studies with a total of 10,514 patients and 11,458 flaps were included for the analysis (Table 1).

Table 1

Summary of included studies and data

Authors (year published, country/region, level) Study design No. patients/flaps (type of flap) Summary of data included in WHO BMI classification Summary of data included in BMI <30 vs. ≥30 kg/m2
BMI (kg/m2) Women [breasts] Minor Major Loss of reconstruction BMI (kg/m2) Women [breasts] Minor Major Loss of reconstruction
Patterson et al. (2022, USA, III) (37) Rc 219/306 [306 DIEP (132 unilateral, 174 bilateral)] 30–34.9 125 [174] 42 25 1 ≥30 219 [306] 83 55 3
35–39.9 49 [69] 17 15 1 Total 219 [306] 83 55 3
≥40 45 [63] 24 15 1
Total 219 [306] 83 55 3
Palve et al. (2022, Finland, III) (38) Rc 308/308 (308 DIEP (unilateral)] <25 104 [104] 13 16 0 <30 246 [246] 34 41 0
25–29.9 142 [142] 21 25 0 ≥30 62 [62] 17 11 0
Total 246 [246] 34 41 0 Total 308 [308] 51 52 0
Heidekrueger et al. (2021, Germany, III)† (39) Rc 3,911/4,561 (4,561 DIEP) <25 1,817 [2,047] NA 189 36 <30 3,227 [3,717] NA 345 71
25–29.9 1,410 [1,670] NA 156 35 ≥30 684 [844] NA 68 21
30–34.9 516 [634] NA 50 17 Total 3,911 [4,561] NA 413 92
Total 3,743 [4,351] NA 395 88
Cheng et al. (2021, Taiwan, III) (40) Rc 415/418 [381 DIEP, 20 SIEA, 17 TRAM (412 unilateral, 3 bilateral)] 18.5–24.9 319 [321] 45 35 3 <30 415 [418] 57 47 5
25–29.9 96 [97] 12 12 2 Total 415 [418] 57 47 5
Total 415 [418] 57 47 5
Munder et al. (2020, Germany, III)† (41) Rc 1,124/1,274 [1,274 DIEP (974 unilateral, 150 bilateral)] <25 502 NA 35 3 <30 954 NA 105 7
25–29.9 452 NA 70 4 ≥30 170 NA 22 1
Total 954 NA 105 7 Total 1124 NA 127 8
Novak et al. (2020, USA, III) (42) Rc 66/123 [63 DIEP, 59 msTRAM, 1 TRAM (9 unilateral, 57 bilateral)] NA ≥30 66 [123] 24 20 4
Total 66 [123] 24 20 4
Sultan et al. (2020, USA, III)† (43) Rc 71/71 (71 DIEP (unilateral)] <25 30 [30] 15 3 0 <30 30 [30] 15 3 0
Total 30 [30] 15 3 0 Total 30 [30] 15 3 0
Ochoa et al. (2019, USA, II)† (44) Pcom 73/130 [130 DIEP (16 unilateral, 57 bilateral)] <25 23 [41] 8 1 0 <30 50 [88] 18 4 0
25–29.9 27 [47] 10 3 0 ≥30 23 [42] 23 2 0
30–34.9 15 [27] 9 0 0 Total 73 [130] 41 6 0
Total 65 [115] 27 4 0
O'neill et al. (2019, Canada, III)† (45) Rc 960/1,460 [1460 DIEP (460 unilateral, 500 bilateral)] <25 243 [340] 14 17 3 <30 598 [887] 46 42 6
25–29.9 355 [547] 32 25 3 ≥30 362 [573] 37 41 7
Total 598 [887] 46 42 6 Total 960 [1,460] 83 83 13
Chang et al. (2018, USA, IV) (46) Pc 72/115 [46 DIEP, 1 SIEA, 67 msTRAM, 1 TRAM (29 unilateral, 43 bilateral)] NA ≥30 72 [115] 21 5 0
Total 72 [115] 21 5 0
Mani et al. (2016, England, III)† (47) Rc 171/171 [171 DIEP (unilateral)] <25 58 [58] 15 3 0 <30 134 [134] 35 9 1
25–29.9 76 [76] 20 6 1 ≥30 37 [37] 24 4 1
Total 134 [134] 35 9 1 Total 171 [171] 59 13 2
Kantak et al. (2015, USA, III) (48) Rc 381/381 [381 DIEP (unilateral)] NA <30 291 [291] 73 38 3
≥30 90 [90] 29 21 2
Total 381 [381] 102 59 5
Ozturk et al. (2014, USA, III)† (49) Rc-c 182/264 [232 DIEP, 6 SIEA, 17 msTRAM, 9 TRAM (100 unilateral, 82 bilateral)] <25 32 [42] 2 5 0 <30 119 [169] 15 27 2
25–29.9 87 [127] 13 22 2 ≥30 63 [95] 28 18 1
Total 119 [169] 15 27 2 Total 182 [264] 43 45 3
Fischer et al. (2013, USA, III)† (50) Rc 812/1,258 [23,1% DIEP, 5,8% SIEA, 71,1% msTRAM (336 unilateral, 476 bilateral)] 30–34.9 170 [273] 97 3 1 <30 540 [830] 222 14 10
35–39.9 56 [81] 33 2 2 ≥30 272 [428] 152 10 7
≥40 46 [74] 22 5 4 Total 812 [1,258] 374 24 17
Total 272 [428] 152 10 7
Garvey et al. (2012, USA, II) (51) Rc NA/548 (162 DIEP, 34 SIEA, 352 msTRAM) NA ≥30 [548] 125 156 8
Total [548] 125 156 8
Ochoa et al. (2012, USA III) (52) Rc 418/639 [639 DIEP (197 unilateral, 221 bilateral)] <25 100 [141] 24 12 0 <30 253 [380] 68 26 3
25–29.9 153 [239] 44 14 3 ≥30 165 [259] 68 12 3
30–34.9 113 [181] 42 11 3 Total 418 [639] 136 38 6
35–39.9 45 [68] 25 1 0
≥40 7 [10] 1 0 0
Total 418 [639] 136 38 6
Jandali et al. (2011, USA, III)† (53) Rc 404/612 [141 DIEP, 42 SIEA, 431 msTRAM (194 unilateral, 210 bilateral)]‡ ≥40 25 [42] 11 6 8 ≥30 25 [42] 11 6 8
Total 25 [42] 11 6 8 Total 25 [42] 11 6 8
Seidenstuecker et al. (2011, Germany, IV) (54) Pc-c 558/624 [400 DIEP, 224 msTRAM (492 unilateral, 66 bilateral)] NA <30 479 [535] NA 22 2
≥30 79 [89] NA 13 3
Total 558 [624] NA 35 5
Garvey et al. (2005, USA, III)† (55) Rc 71/80 [DIEP (62 unilateral, 9 bilateral)] <25 33 [35] 7 4 0 <30 59 [65] 13 12 3
25–29.9 26 [30] 6 8 3 ≥30 12 [15] 5 3 0
Total 59 [65] 13 12 3 Total 71 [80] 18 15 3
Chang et al. (2000, USA IV)† (56) Pc 718/936 [936 TRAM (76.7% unilateral, 23.3% bilateral)] <25 442 46 64 0 <30 654 76 113 4
25–29.9 212 30 49 4 ≥30 64 13 20 2
Total 654 76 113 4 Total 718 89 133 6

Outcome comparison between BMI groups stratified according to ‘WHO classification’ and in ‘≥30 kg/m2 (obese) and <30 kg/m2 (non-obese)’. Outcome analyzed per woman and per breast. †, only data compatible to BMI classification excluded from study; ‡, the total number of flaps, as per the information drawn from the article, does not match the sum of the three different types of flaps as stated in the article. DIEP, deep inferior epigastric perforator; TRAM, transverse rectus abdominis musculocutaneous; msTRAM, muscle-sparing TRAM; SIEA, superficial inferior epigastric artery; BMI, body mass index; WHO, World Health Organization; Rc, retrospective cohort; Pcom, prospective comparative; Pc, prospective cohort; Rc-c, retrospective case-control; Pc-c, prospective case-control; NA, not applicable/not announced.

Mean age was 50.7 years, stated in 18 papers, ranging from 45.3 to 53.6 years (37-53,55), and current smokers status varied from 0% to 15.2% (46,54). As for the timing of reconstruction, 1 study included delayed breast reconstruction (38), 16 included both immediate and delayed reconstruction and 3 studies did not specify the timing of reconstruction (54-56). One study stratified complications by BMI and immediate or delayed reconstruction (51).

Twenty studies (100%) reported the incidence of major complications and loss of reconstruction, 3 studies (15%) did not report minor complications (39,41,54).

Of the 20 included studies, 4 reported on unilateral breast reconstruction solely, and 16 comprised both unilateral and bilateral breast reconstruction. Two studies reported the stages of BC (40,55). Extraction of study parameters relating to pre- and postoperative radiation therapy, chemotherapy and hormone therapy was undertaken. Due to limited data availability and small cohort sizes, statistical analyses or trend assessments were not performed.

Follow-up was stated in 15 of 20 papers, ranging from 1 to 135 months (40,49).

Risk of bias and level of evidence

The papers were ranked according to the level of evidence (36). The papers included were primarily of lower levels of evidence. Two studies were found to be level II. Fifteen studies corresponded to evidence level III, and three studies level IV (Table 1).

The majority of the included studies were retrospective studies and may therefore be prone to observer and recall bias. Methodological weakness was found in all 20 studies, primarily due to lack of description of potential bias and study size calculation. Three studies were considered to have a low risk of bias, 12 studies were considered to have moderate risk of bias and five studies were identified to have a serious risk of bias (Table 2).

Table 2

Risk of bias

Study Title and abstract Introduction Methods Results Discussion Other information Overall risk of bias
Patterson et al. (37), 2022 + + − − + − Moderate
Palve et al. (38), 2022 + + − + + + Moderate
Heidekrueger et al. (39), 2021 + + − − + + Moderate
Cheng et al. (40), 2021 + + − − + + Moderate
Munder et al. (41), 2020 + + − + − − Moderate
Novak et al. (42), 2020 + + − + + + Moderate
Sultan et al. (43), 2020 + + − − − + Serious
Ochoa et al. (44), 2019 + + − + + + Low
O'neill et al. (45), 2019 + + − + + + Moderate
Chang et al. (46), 2018 + + − − + + Serious
Mani et al. (47), 2016 + + − + + − Moderate
Kantak et al. (48), 2015 + + − − + − Moderate
Ozturk et al. (49), 2014 + + − + + + Moderate
Fischer et al. (50), 2013 + + − + + + Low
Garvej et al. (51), 2012 + + − + + + Low
Ochoa et al. (52), 2012 + + − + − + Moderate
Jandali et al. (53), 2011 + + − − − + Serious
Seidenstuecker et al. (54), 2011 + + − − − + Serious
Garvej et al. (55), 2005 + + − + + − Moderate
Chang et al. (56), 2000 + + − + − − Serious

Studies are assessed as sufficient (+) or insufficient (−) within each domain.

Analyses

Analysis of complications comparing obese (BMI ≥30 kg/m2) vs. non-obese (BMI <30 kg/m2) patients

In the obese/non-obese comparison, 18 studies were included for analysis per breast and 19 studies per woman (Table 3).

Table 3

Pooled outcome measurements

BMI (kg/m2) Breasts/women, n (%) Minor Major Loss of reconstruction
N (%)† Odds ratio (95% CI) P value N (%) Odds ratio (95% CI) P value N (%) Odds ratio (95% CI) P value
<30
   Breasts 7,817 (68.2) 596 (16.7) NA NA 630 (8.1) NA NA 106 (1.4) NA NA
   Women 8,049 (76.6) 672 (19.8) 848 (10.5) 117 (1.5)
≥30
   Breasts 3,641 (31.8) 647 (23.9) 1.6 (1.4–1.8) 3.3×10−59* 445 (12.2) 1.6 (1.4–1.8) 1.4×10−12* 68 (1.9) 1.4 (1.0–1.9) 0.045*
   Women 2,465 (23.4) 535 (34.9) 2.2 (1.9–2.5) 1.0×10−73* 331 (13.4) 1.3 (1.1–1.5) 7.9×10−5* 63 (2.6) 1.8 (1.3–2.4) 3.2×10−4*
Total
   Breasts 11,458 1,243 (19.8) 1.2 (1.1–1.4) 2.1×10−4* 1,075 (9.4) 1.2 (1.1–1.3) 1.6×10−3* 174 (1.5) 1.1 (0.9–1.4) 0.38
   Women 10,514 1,207 (24.5) 1.3 (1.2–1.5) 5.6×10−7* 1,179 (11.2) 1.1 (0.9–1.2) 0.15 180 (1.7) 1.2 (0.9–1.5) 0.18

≥30 kg/m2 (obese) compared with <30 kg/m2 (non-obese) per breast and women with odds ratios and P values. †, the percentages reflect calculations based on the sum of patients or breasts from the included articles that report on minor complications, rather than the overall total. *, P value <0.05. BMI, body mass index; CI, confidence interval; NA, not applicable/not announced.

The obese group had statistically significant higher odds ratio (OR) of minor complications (OR, 1.6), major complications (OR, 1.6) and loss of reconstruction (OR, 1.4) in the analysis per breast.

When comparing complications per woman, OR for minor complications (OR, 2.2), major complications (OR, 1.3) and loss of reconstructions (OR, 1.8) were significantly higher for the obese group.

Analysis of complications per breast according to WHO BMI classification

The overweight (BMI 25–29.9 kg/m2), class I (BMI 30–34.9 kg/m2), class II (BMI 35–39.9 kg/m2) and class III obese (BMI ³40 kg/m2) groups were compared to the normal weight group (BMI 18.5–24.9 kg/m2). Thirteen studies were included for analysis according to WHO’s BMI classification per breast (Table 4). Significant higher OR of minor complications were found in the class I (OR, 2.8), class II (OR, 3.6), and class III obese (OR, 3.0).

Table 4

Pooled outcome measurements

BMI (kg/m2) Breasts/women, n (%) Minor Major Loss of reconstruction
N (%)† Odds ratio (95% CI) P value N (%) Odds ratio (95% CI) P value N (%) Odds ratio (95% CI) P value
<25
   Breasts 3,159 (40.0) 143 (11.7) NA NA 285 (9.0) NA NA 42 (1.3) NA NA
   Women 3,703 (46.6) 189 (13.7) 384 (10.4) 45 (1.2)
25–29.9
   Breasts 2,975 (38.0) 158 (10.5) 0.9 (0.7–1.2) 0.62 271 (9.1) 1.0 (0.8–1.2) 0.94 49 (1.6) 1.2 (0.8–1.9) 0.36
   Women 3,036 (38.2) 188 (16.0) 1.2 (0.9–1.5) 0.18 390 (12.8) 1.3 (1.1–1.5) 1.7×10–3* 57 (1.9) 1.6 (1.1–2.3) 0.03*
30–34.9
   Breasts 1,289 (16.5) 190 (14.7) 2.8 (2.2–3.5) 8.8×10−17* 89 (6.9) 0.7 (0.6–0.9) 0.025* 22 (1.7) 1.3 (0.8–2.2) 0.4
   Women 939 (11.8) 190 (20.2) 5.2 (4.0–6.6) 3.1×10–41* 89 (9.5) 0.9 (0.7–1.2) 0.42 22 (2.3) 1.9 (1.2–3.3) 0.015*
35–39.9
   Breasts 218 (2.8) 75 (34.4) 3.6 (2.6–4.9) 8.7×10–15* 18 (8.3) 0.9 (0.6–1.5) 0.8 3 (1.4) 1.0 (0.3–3.4) 0.76
   Women 150 (1.9) 75 (50.0) 6.3 (4.4–9.0) 1.8×10–27* 18 (12.0) 1.2 (0.7–2.0) 0.6 3 (2.0) 1.7 (0.5–5.4) 0.43
≥40
   Breasts 189 (2.4) 58 (30.7) 3.0 (2.1–4.3) 7.2×10–10* 26 (13.8) 1.6 (1.0–2.5) 0.04* 7 (3.7) 2.9 (1.3–6.4) 0.018*
   Women 123 (1.5) 58 (47.2) 5.6 (3.8–8.3) 1.6×10–20* 26 (21.1) 2.3 (1.5–3.6) 2.6×10–4* 7 (5.7) 4.9 (2.2–11.1) 1.2×10–3*
Total
   Breasts 7,830 624 (17.9) 1.5 (1.2–1.8) 9.5×10–5* 689 (8.8) 1.0 (0.8–1.1) 0.74 123 (1.6) 1.2 (0.8–1.7) 0.39
   Women 7,951 700 (10.3) 1.7 (1.5–2.1) 6.5×10–10* 907 (11.4) 1.1 (0.9–1.3) 0.1 134 (1.7) 1.4 (1.0–2.0) 0.06

WHO BMI classification per breast and women with odds ratios and P values. Odds ratio and P value for each BMI group is compared/in relation to BMI <25 kg/m2. †, the percentages reflect calculations based on the sum of patients or breasts from the included articles that report on minor complications, rather than the overall total. *, P value <0.05. BMI, body mass index; CI, confidence interval; NA, not applicable/not announced; WHO, World Health Organization.

Analyzing major complications, the class I group had significant lower OR of major complications (OR, 0.7). OR major complications (OR, 1.6) and loss of reconstruction (OR, 2.9) were significant higher in the class III group (Table 4).

Analysis of complications per woman according to WHO BMI classification

Fifteen studies were included for analysis according to WHO’s BMI classification per woman (Table 4). The analysis per woman showed similar significant OR for the three outcome measurements. Significant higher OR of minor complications were found in the class I (OR, 5.2), class II (OR, 6.3) and class III obese (OR, 5.6). The class I group had significant higher OR of loss of reconstruction (OR, 1.9). The overweight group showed significant higher OR of major complications (OR, 1.3) and loss of reconstruction (OR, 1.6). Similar to the per breast analysis, the class III obese group showed significant higher OR for major complications (OR, 2.3) and loss of reconstruction (OR, 4.9) (Table 4).

Discussion

This systematic review investigated the association between BMI and postoperative complications at the recipient site after autologous breast reconstruction based on free abdominal-based flaps.

A total of 10,514 patients and 11,458 flaps were included in 4 subgroup analyses. The complications were analyzed per breast and per woman. The total number of breasts and women varied within the different BMI groups, but pooled data showed similar results analyzing complications per breast and per woman.

In the obese group analyses yielded significantly higher complication rates for all three outcomes when compared to the non-obese group. Our results are comparable to previous studies reporting increased risk of overall complications (47,57,58), minor complications (4,49,51,52,55,57), major complications (54), and loss of reconstruction (53).

Comparing the normal weight group to the three obesity classes defined by WHO, each group showed significant higher risk of minor complications. Results are comparable to previously reported complication rates (41,45,49,50,53,58-60).

The overweight and class III obesity groups both showed significant higher risk of loss of reconstruction. These results are similar to Jandali et al.’s report on class III obesity group having significantly higher rates of loss of reconstruction and total major complications (53).

However, not all studies report this correlation. Ochoa et al. found no statistical difference in major complications or total flap failure, when comparing overweight, class I, class II and class III obese patients with the normal weight group in 418 patients and 639 flaps (52).

Though obesity and increased minor complication rates are associated, this study shows that major complications and total flap failures in the overweight and obese groups remains equal to the normal weight group. Risk of loss of reconstruction was significant higher for the class III obese group, indicating that patients with BMI ³40 kg/m2 are not candidates for an autologous breast reconstruction (Figure 2).

Figure 2 Odds ratio loss of reconstruction. WHO BMI classification per breast and women. WHO, World Health Organization; BMI, body mass index.

In the population with BMI between ³30 and <40 kg/m2, obesity may not be a contraindication for autologous breast reconstruction with DIEP, SIEA, msTRAM or TRAM flaps.

However, a weight loss prior to reconstructive surgery should be recommended to obese patients optimizing safety and minimizing the increased risk of complications. It has previously been reported that preoperative weight loss facilitates reconstruction and improves outcomes in obese patients following a breast reconstruction (49,61). The class III obese had significantly higher complication rates on all three outcome measurements, indicating a need for a more specific BMI threshold before surgery.

Balancing risks of complications to the positive effect on quality of life as reported in previous studies (44,62-64), an autologous breast reconstruction may still be the best option despite the risk of minor complications in selected patient cases.

Strengths and limitations

This systematic review included a large patient population, allowing comprehensive analyses of the correlation between BMI and postoperative complications, in addition analysis of BMI subgroups and postoperative complication were chosen to give a more precise correlation of the effect of the different BMI groups. All analyses were conducted both per patient and per breast. Classifying BMI according to WHO provides a more nuanced insight into different weight groups and a more precise analysis of BMI threshold for breast reconstruction. This study may be limited due to the heterogeneity of the included flaps and included studies, both regarding designs, definition of complications and the quality and evidence level. Moreover, results have not been adjusted for the effects of immediate/delayed or unilateral/bilateral reconstructions, age or smoking, which may limit the conclusions to be drawn from this systematic review. Insufficient information about the management of flap complications from the included studies may have resulted in incorrect subgroup complication classification by the authors.

Conclusions

This review finds that BMI has an effect on the incidence of postoperative complications at the recipient site after autologous breast reconstruction.

The obese population (BMI ³30 kg/m2) has an increased risk of both minor and major complications and loss of reconstruction compared to the non-obese population.

Grouping BMI according to WHO classification, risks of minor complications are increased in all obesity classes (BMI 30–34.9, BMI 35–39.9 and BMI ³40 kg/m2). Despite the increased risk of minor complication in the obese groups, autologous breast reconstruction may still be the best option for this population in selected cases.

Overall, this study indicates a BMI £40 kg/m2 as surgical threshold for autologous breast reconstruction based on free abdominal flaps, where the risk of loss of reconstruction is drastically increased. Considering the high rates of complications among patients with a BMI exceeding 30 kg/m2 who undergo breast reconstruction, it is advisable to provide thorough counselling about the risks and possible delay in reconstruction until weight loss has been achieved.

Further studies on a higher level of evidence are needed to investigate the impact of BMI on autologous breast reconstruction, as well as the effect of immediate or delayed reconstruction on complications.

Acknowledgments

Our abstract was accepted for presentation at the 11th EURAPS Research Counsil meeting, Stockholm, Sweden, which took place between the 24th and 25th of May 2023.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the PRISMA reporting checklist. Available at https://abs.amegroups.com/article/view/10.21037/abs-23-46/rc

Peer Review File: Available at https://abs.amegroups.com/article/view/10.21037/abs-23-46/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://abs.amegroups.com/article/view/10.21037/abs-23-46/coif). T.E.D. serves as an unpaid editorial board member of Annals of Breast Surgery from July 2023 to June 2025. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring the questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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doi: 10.21037/abs-23-46
Cite this article as: Frid NL, Lauritzen E, Damsgaard TE. A systematic review on the association between body mass index and autologous breast reconstruction. Ann Breast Surg 2024;8:18.

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