Patient-reported outcomes in masculinizing gender-affirming chest surgery: validation of the GENDER-Q Chest scales

Abstract

Background

Masculinizing gender-affirming chest surgery is the most frequently accessed type of gender-affirming procedure. The GENDER-Q Chest scales were developed to better assess patient-reported outcomes in masculinizing gender-affirming chest surgery, yet previous psychometric assessment of these scales is limited. The aim of this study was to assess the construct validity of the GENDER-Q Chest scales (Chest, Nipples & Areolas, and Scars).

Methods

An international, cross-sectional study was performed to develop the GENDER-Q between February 2022 and March 2024. Individuals were included in this analysis if they had sought or received masculinizing gender-affirming chest surgery and completed the GENDER-Q Chest scale. Construct validity was assessed for each scale by testing a priori hypotheses. According to Consensus-based Standards for the Selection of Health Measurement Instruments guidelines, at least 75% acceptance of hypotheses indicates sufficient evidence of construct validity.

Results

A total of 2846 participants completed the GENDER-Q Chest scale. For the GENDER-Q Chest, Nipples & Areolas, and Scars scales, 95% (21 of 22), 79% (15 of 19), and 100% (12 of 12) of hypotheses were accepted for each scale respectively. Patients who had undergone surgery and did not need revisions at survey completion reported the highest satisfaction, while patients who had not yet undergone surgery reported the lowest satisfaction.

Conclusion

The GENDER-Q Chest scales evidenced construct validity to measure appearance of chest, nipples and areolas, and scars for individuals seeking or undergoing masculinizing gender-affirming chest surgery. The GENDER-Q Chest scales provide a robust, validated approach for assessing outcomes in this context and are well suited for generating high-quality evidence on patient-reported outcomes.

This international, cross-sectional study evaluated the construct validity of the GENDER-Q Chest scales, designed to assess patient-reported outcomes in masculinizing gender-affirming chest surgery. Among 2846 participants, the GENDER-Q Chest scales demonstrated sufficient construct validity, with at least 75% of hypotheses accepted for each scale, confirming their accuracy for measuring patient-reported outcomes in this population. These validated scales enable high-quality research on satisfaction and appearance-related outcomes for individuals seeking or undergoing masculinizing chest surgery.

Introduction

Gender-affirming care is essential for the estimated 1–3% of individuals worldwide who identify as transgender or gender-diverse (TGD)¹. Over the past 15 years, gender-affirming surgical procedures have increased substantially, with masculinizing gender-affirming chest surgery being the most common². There is growing interest in understanding the outcomes from these procedures, including calls for higher-quality research from patients, providers, and policymakers alike^3–5. Patient-reported outcome measures (PROMs) are increasingly used to evaluate outcomes that matter most to patients⁶. These tools are valuable because conventional surgical metrics, such as complication rates, length of stay, and reoperation rates, often fail to measure outcomes related to individual patient goals and therefore may not capture the true impact of these procedures on patients’ lives⁷.

Previous PROM studies of masculinizing gender-affirming chest surgery report far-reaching benefits, including improved satisfaction with appearance, body image, quality of life, and psychosocial outcomes, with low rates of regret^8–15. Despite these positive results, systematic reviews examining how patient-reported outcomes (PROs) are measured in gender-affirming surgery have demonstrated that the current literature relies on a range of instruments, most of which were not designed or validated for use in TGD populations undergoing gender-affirming surgery^16–18. Using PROMs not specifically designed for the population of interest, and PROMs that lack psychometric evidence, weakens the credibility of findings, complicates clinical application, and hinders care guideline development¹⁹. The lack of standardized PROMs also limits data comparison across studies. In response, the GENDER-Q was created to provide a comprehensive and globally applicable instrument to measure PROs across the spectrum of gender-affirming care^6,20–22. Prior work demonstrated strong psychometric evidence for the GENDER-Q Chest scales, including content validity, internal consistency, and test-retest reliability (Table S1)²². However, comprehensive evaluation of construct validity had not been completed, which is crucial for confirming a PROM’s clinical value. Construct validity refers to how accurately an instrument measures its intended theoretical concept^23,24.

The aim of this study was to provide evidence for the construct validity of the three GENDER-Q Chest scales that measure appearance of the chest, nipples and areolas, and scars. Hypothesized relationships of these three scales with clinical variables and other GENDER-Q scales were evaluated to establish their validity for assessing chest satisfaction in masculinizing gender-affirming chest surgery.

Methods

Data source

A cross-sectional study was conducted to develop and validate the GENDER-Q through an international field test²². Ethical approval was obtained from the Hamilton Integrated Research Ethics Board (#13171) and from collaborating sites.

Participant recruitment

Detailed data collection methods are available in Kaur et al.²² (published in 2025). TGD individuals were recruited from clinical sites and community groups to participate in the GENDER-Q international field test between February 2022 and March 2024. Individuals were eligible to take part in the study if they were aged ≥18 years and had sought or received gender-affirming care within the past 5 years. Participants completed an online survey in REDCap (Research Electronic Data Capture, Vanderbilt University, Nashville, TN, USA)^25,26. The survey contained demographics, clinical questions, GENDER-Q scales, and psychometric validation items. Branching logic was used to ensure participants were asked only relevant, required questions, while all other questions were optional. The GENDER-Q Chest scales were only shown to participants who wanted or had previously undergone masculinizing gender-affirming chest surgery. For data analysis, participants were included if they completed the Chest scale. Completion of each scale was optional; consequently, some participants may not have completed the Nipples & Areolas scale or the Scars scale.

Outcomes

Demographic and clinical data

Participants answered questions regarding demographics, chest appearance preference (masculinizing, feminizing, other), testosterone use (yes, no; duration), and chest surgery status (want, had, had and currently need revisions). Participants who underwent surgery answered clinical questions regarding surgical technique, time since surgery, complications, revisions, perceived nipple position, and number of nipples.

GENDER-Q Chest scales

The GENDER-Q comprises 54 independently functioning scales and two checklists^21,22; this study focuses on the Chest, Nipples & Areolas, and Scars scales (Table 1). The Chest scale measures current satisfaction with chest appearance. The Nipples & Areolas scale measures current satisfaction with nipple and areola appearance. The Scars scale assesses how bothered individuals are with the appearance of their chest scars. The content for the Scars scale is from the SCAR-Q, which was previously developed by Klassen et al.²⁷ The Chest and Nipples & Areolas scales can be used before surgery and after surgery, while the Scars scale is only relevant after surgery. To score each scale, each items’ associated response value is summed to generate a raw score. The raw score is then transformed using Rasch-transformed values that range from 0 (worst) to 100 (best). Missing data are imputed via within-person mean imputation if ≥50% of the scale’s items are complete. Other GENDER-Q scales utilized in this study included the Body scale, the Sexual Well-being scale, and five Health-Related Quality of Life (HRQL) scales (Body Image, Gender Dysphoria, Social Acceptance, Psychological Distress, and Psychological Well-being) (Table 1).

Table 1.

GENDER-Q scales used

GENDER-Q domain	GENDER-Q scale	PROM construct	Number of questions	Response options
Chest	Chest	Current satisfaction with appearance of chest	10	6 (extremely dissatisfied to extremely satisfied)
	Nipples & Areolas	Current satisfaction with appearance of nipples and areolas	8	6 (extremely dissatisfied to extremely satisfied)
	Scars	Current bother with scar appearance	12	4 (very much to not at all)
Body	Body	Current satisfaction with body appearance	10	6 (extremely dissatisfied to extremely satisfied)
Sexual	Sexual Well-being	Frequency of feeling positive towards sexual activity generally	12	5 (never to always)
Health-Related Quality of Life (HRQL)	Body Image	Frequency of feeling satisfied with appearance over the past week	8	5 (never to always)
	Gender Dysphoria	Frequency gender dysphoria interfering with daily life over the past week	14	5 (never to always)
	Social Acceptance	Frequency of impact of gender identity on social well-being over the past week	9	5 (never to always)
	Psychological Distress	Frequency of experiencing gender-related distress over the past week	10	5 (never to always)
	Psychological Well-being	Frequency of feeling positive emotions related to gender identity over the past week	10	5 (never to always)

All scales are scored from 0 (worst possible score) to 100 (best possible score). PROM, patient-reported outcome measure.

Statistical analysis

Analyses were conducted in SPSS (IBM, Armonk, NY, USA; version 30). Descriptive statistics were calculated for the GENDER-Q Chest scales. Statistical significance was set at α = 0.050. Kurtosis (absolute >7) and skewness (absolute >2) were used to assess substantial non-normality²⁸. Psychometric analyses were guided by the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines^29–31. Construct validity was determined for each scale by testing a priori hypotheses. According to COSMIN guidelines, acceptance of at least75% of these hypotheses is considered sufficient evidence of construct validity. Hypotheses were formulated based on available evidence, clinical reasoning, and participant feedback during qualitative interviews. Hypotheses reflected expected group-level differences and correlations between GENDER-Q Chest scales and other GENDER-Q scales. Group-level differences were assessed using an independent-sample t test or ANOVA or the equivalent non-parametric test for data not normally distributed. If the hypothesis stated directionality, a one-sided t test was applied; all other tests were two-sided. Correlations between scales were assessed using the Pearson correlation coefficient, with values of <0.3 indicating unrelated constructs, values of 0.3 to <0.5 indicating related but dissimilar constructs, and values of ≥0.5 indicating similar constructs³².

Results

In total, 2846 participants completed the Chest scale, 2523 participants completed the Nipples & Areolas scale, and 1921 participants completed the Scars scale (Fig. S1). The mean(s.d.) age of the sample was 29.3(9.6) years, with a range of 18–74 years. Most identified as male (61.6%) or non-binary (32.0%), were White (75.5%), and lived in the USA (47.5%) or Canada (32.2%). Most (78.9%) completed the scale after surgery and 86.6% of those who underwent surgery had a double incision mastectomy. Full demographic and clinical details are shown in Table 2.

Table 2.

Self-reported demographic and clinical characteristics of the study sample for the GENDER-Q chest scales (n = 2846)

	Values
Age at survey completion (years)
18–24	1068 (37.5)
25–29	725 (25.5)
30–39	690 (24.2)
40–49	216 (7.6)
≥50	147 (5.2)
Gender identity
Man	1738 (61.1)
Non-binary	912 (32.0)
Indigenous or other cultural gender minority identity (for example two-spirit)	25 (0.9)
Other	171 (6.0)
Sex assigned at birth
Female	2846 (100.0)
Country of residence
Australia	155 (5.4)
Canada	917 (32.2)
Denmark	88 (3.1)
Netherlands	55 (1.9)
UK	126 (4.4)
USA	1353 (47.5)
Other	149 (5.2)
Prefer not to answer	3 (0.1)
Race
Black	108 (3.8)
East Asian	48 (1.7)
Indigenous	24 (0.8)
Latin American	82 (2.9)
Middle Eastern	26 (0.9)
South Asian	18 (0.6)
Southeast Asian	31 (1.1)
White	2148 (75.5)
Other	8 (0.3)
Multiple races	327 (11.5)
Prefer not to answer	21 (0.7)
Missing	5 (0.2)
Education level
Some high school	104 (3.7)
Completed high school	377 (13.2)
Some college or trade school or university	787 (27.7)
Completed college or trade school or university	1019 (35.8)
Some masters or doctoral degree	166 (5.8)
Completed masters or doctoral degree	386 (13.6)
Prefer not to answer	7 (0.2)
Chest surgery status
‘I want this’	601 (21.1)
‘I had this’	2012 (70.7)
‘I had this and need more’	233 (8.2)
Type of chest surgery
Double incision	1944 (86.6)
T-anchor	62 (2.8)
Circumareolar	63 (2.8)
Periareolar	148 (6.6)
Other chest surgery	24 (1.1)
I am not sure	4 (0.2)
Time since surgery
≤6 months	309 (13.8)
7 to <12 months	332 (14.8)
1 to <2 years	335 (14.9)
2 to <3 years	352 (15.7)
3 to <4 years	219 (9.8)
4 to <5 years	177 (7.9)
≥5 years	520 (23.2)
Missing	1 (0.0)
Complications
Haematoma	198 (8.8)
Seroma	287 (12.8)
Surgical-site infection	157 (7.0)
Revisions
Lateral standing cutaneous deformity revision
Do not need	1387 (61.8)
Need	471 (21.0)
Completed	142 (6.3)
Not sure	242 (10.8)
Missing	3 (0.1)
Chest contour revision
Do not need	1350 (60.1)
Need	310 (13.8)
Completed	287 (12.8)
Not sure	289 (12.9)
Missing	9 (0.4)
Excess tissue removal
Do not need	1719 (76.6)
Need	144 (6.4)
Completed	178 (7.9)
Not sure	189 (8.4)
Missing	15 (0.7)
Hypopigmentation correction
Do not need	1849 (82.4)
Need	134 (6.0)
Completed	13 (0.6)
Not sure	228 (10.2)
Missing	21 (0.9)
Nipple revision
Do not need	1728 (77.0)
Need	216 (9.6)
Completed	53 (2.4)
Not sure	239 (10.6)
Missing	9 (0.4)
Scar revision
Do not need	1605 (71.5)
Need	254 (11.3)
Completed	73 (3.3)
Not sure	294 (13.1)
Missing	19 (0.8)
Number of nipples
Two	1923 (85.7)
One—assumed postoperative complication	55 (2.4)
Zero—assumed postoperative complication	64 (2.9)
Zero—nipples removed during surgery per patient preference	189 (8.4)
Prefer not to answer	5 (0.2)
Missing	9 (0.4)
Perceived nipple position of participants with two nipples
Appropriately positioned	1686 (87.7)
Malpositioned	229 (11.9)
Prefer not to answer	8 (0.4)

Values are n (%).

Construct validation

GENDER-Q Chest

Of the 22 hypotheses assessed for the GENDER-Q Chest scale, 1 was rejected, resulting in an acceptance rate of 95% (Table 3).

Table 3.

Summary of hypotheses tested for construct validity of the GENDER-Q chest scales

Construct validity hypotheses	GENDER-Q Chest scales
	Chest	Nipples & Areolas	Scars
Group-level difference hypotheses
1. Participants who had surgery without needing revisions will score higher on scales than those who had surgery and needed revisions or those who want surgery*	Y	Y	NA
2. Participants who are ≤6 months postoperative will score lower on scales than those who are >6 months postoperative, given that patients’ chests often take 4–6 months to fully heal after masculinizing gender-affirming chest surgery†	N	N	NA
3. Participants who report having specific complications will score lower on scales than those who did not have those specific complications‡§
a. Haematoma	Y	Y	NA
b. Seroma	Y	Y	NA
c. Surgical-site infection	Y	Y	NA
4. Participants who report needing specific revisions will score lower on scales than those who did not need those specific revisions*
a. Lateral standing cutaneous deformity revision	Y	NA	NA
b. Chest contour revision	Y	NA	NA
c. Excess tissue removal	Y	NA	NA
d. Hypopigmentation correction	Y	Y	Y
e. Nipple revision	Y	Y	NA
f. Scar revision	Y	NA	Y
5. Participants who report that their nipples are located in the right place for them will score higher on scales than those who report the nipples are located in the wrong place¶#	Y	Y	NA
6. Participants who report having two nipples will score higher on scales than those who have one‡¶	Y	Y	NA
7. Participants who underwent periareolar procedures will score higher on scales than those who underwent double incision procedures, given that double incision procedures produce more scarring, discoloration, and wound healing complications associated with nipple grafts**	NA	N	Y
Correlation hypotheses
1. Chest (≥0.5 Nipples & Areolas; 0.3 to <0.5 Scars)†	NA	Y	Y
2. Nipples & Areolas (≥0.5 Chest; 0.3 to <0.5 Scars)†	Y	NA	Y
3. Scars (0.3 to <0.5 Chest, Nipples & Areolas)†	Y	Y	NA
4. Body (≥0.5 Chest; 0.3 to <0.5 Nipples & Areolas; <0.3 Scars)†	Y	N	Y
5. Sexual Well-being (0.3 to <0.5 Chest, Nipples & Areolas; <0.3 Scars)†	Y	N	Y
6. Body Image (≥0.5 Chest; 0.3 to <0.5 Nipples & Areolas; <0.3 Scars)†	Y	Y	Y
7. Gender Dysphoria (0.3 to <0.5 Chest, Nipples & Areolas; <0.3 Scars)†	Y	Y	Y
8. Social Acceptance (0.3 to <0.5 Chest, Nipples & Areolas; <0.3 Scars)†	Y	Y	Y
9. Psychological Distress (0.3 to <0.5 Chest, Nipples & Areolas; <0.3 Scars)†	Y	Y	Y
10. Psychological Well-being (0.3 to <0.5 Chest, Nipples & Areolas; <0.3 Scars)†	Y	Y	Y
Number of hypotheses tested	22	19	12
Number of hypotheses accepted	21	15	12
Number of hypotheses rejected	1	4	0
Percentage of hypotheses accepted	95%	79%	100%

^*van de Grift TC, Elfering L, Greijdanus M, Smit JM, Bouman M-B, Klassen AF et al. Subcutaneous mastectomy improves satisfaction with body and psychosocial function in trans men: findings of a cross-sectional study using the BODY-Q chest module. Plast Reconstr Surg 2018;142:1125–1132. †Expert opinion. ‡Berkowitz R, Vu J, Brummett C, Waljee J, Englesbe M, Howard R. The impact of complications and pain on patient satisfaction. Ann Surg 2021;273:1127–1134. §Archer S, Pinto A, Vuik S, Bicknell C, Faiz O, Byrne B et al. Surgery, complications, and quality of life: a longitudinal cohort study exploring the role of psychosocial factors. Ann Surg 2019;270:95–101. ¶Black CK, Fan KL, Economides JM, Camden RC, Del Corral GA. Analysis of chest masculinization surgery results in female-to-male transgender patients: demonstrating high satisfaction beyond aesthetic outcomes using advanced linguistic analyzer technology and social media. Plast Reconstr Surg Glob Open 2020;8:e2356. #Ayyala HS, Mukherjee TJ, Le TM, Cohen WA, Luthringer M, Keith JD. A three-step technique for optimal nipple position in transgender chest masculinization. Aesthet Surg J 2020;40:NP619–NP625. **Rifkin WJ, Robinson IS, Kloer C, Cripps CN, Boyd CJ, Blasdel G et al. Gender-affirming mastectomy: comparison of periareolar and double incision patterns. Plast Reconstr Surg Glob Open 2022;10:e4356. N, no—hypothesis rejected; NA, hypothesis not tested; Y, yes—hypothesis accepted.

Group-level differences for the Chest scale are shown in Table S2. As hypothesized, Chest scale scores varied by surgical status. Preoperative participants reported the lowest scores (23.0(14.6)), followed by participants who had undergone surgery and needed revisions at survey completion (59.0(19.0), P < 0.001), and those who had undergone surgery and did not need revisions at survey completion reported the highest scores (79.5(17.2), P < 0.001) (Fig. 1a). Regarding complications and revisions, as hypothesized: participants with postoperative complications scored lower than those who did not report any complications (P ≤ 0.002); and participants who reported not needing revisions scored higher than those who had completed or needed future revisions (P < 0.001). As expected, participants with two nipples had higher scores compared with those with one nipple (P = 0.028) and participants who thought that their nipples were appropriately positioned had higher scores compared with those who thought they were malpositioned (P < 0.001). Contrary to the hypothesis, participants who were ≤6 months postoperative had statistically higher scores compared with participants who were >6 months postoperative (79.5(17.5) versus 77.0(18.6), P = 0.013), although this difference may not be clinically significant.

Figure 1.

GENDER-Q Chest scale scores according to surgical status (Chest and Nipples & Areolas) or revision status (Scars)

a Mean GENDER-Q Chest scale scores according to surgical status. b Mean GENDER-Q Nipples & Areolas scale scores according to surgical status. c Mean GENDER-Q Scars scale scores according to revision status (GENDER-Q Scars scale can only be completed after surgery). *Significant (P < 0.050), with the value for the first bar as the reference.

Correlations between the Chest scale and other GENDER-Q scales are shown in Table S3. The Scars scale, Sexual Well-being scale, and most HRQL scales demonstrated related but dissimilar constructs to the Chest scale, as expected (r = 0.3 to <0.5, P < 0.001). The Nipples & Areolas, Body, and Body Image scales demonstrated similar constructs to the Chest scale, as expected (r ≥ 0.5, P < 0.001).

GENDER-Q Nipples & Areolas

Of the 19 hypotheses assessed for the GENDER-Q Nipples & Areolas scale, 4 were rejected, resulting in an acceptance rate of 79% (Table 3).

Group-level differences for the Nipples & Areolas scale are shown in Table S2. As hypothesized, Nipples & Areolas scale scores varied by surgical status. Preoperative participants reported the lowest scores (43.0(17.4)), followed by participants who had undergone surgery and needed revisions at survey completion (48.8(14.8), P < 0.001), and those who had undergone surgery and did not need revisions at survey completion reported the highest scores (69.6(19.2), P < 0.001) (Fig. 1b). Participants without complications (P ≤ 0.011) and who did not need revisions (P < 0.001) scored higher on the Nipples & Areolas scale, as expected. Additionally, as hypothesized: those who only had one nipple had lower scores compared with those who had both nipples (P < 0.001); and participants who reported that their nipples were appropriately positioned had higher scores compared with those who thought they were malpositioned (P < 0.001). Contrary to the hypothesis, participants who were ≤6 months postoperative had higher scores compared with participants who were >6 months postoperative (67.3(20.1) versus 64.7(20.3), P = 0.037), although this difference may not be clinically significant. Another hypothesis that was rejected was the expectation that participants who underwent periareolar mastectomies would report higher satisfaction compared with participants who underwent double incision mastectomy with free nipple grafting. This difference was not observed (66.4(18.7) versus 65.7(20.2), P = 0.339).

Correlations between the Nipples & Areolas scale and other GENDER-Q scales are shown in Table S3. The Scars and HRQL scales were considered related but dissimilar constructs to the Nipples & Areolas scale, as expected (r = 0.3 to <0.5, P < 0.001). The Chest scale was considered a similar construct to the Nipples & Areolas scale, as hypothesized (r = 0.6, P < 0.001). The Sexual Well-being scale was considered an unrelated construct to the Nipples & Areolas scale, showing a weaker correlation than hypothesized (r = 0.2, P < 0.001). The Body scale was considered a similar construct to the Nipples & Areolas scale, a stronger correlation than expected (r = 0.5, P < 0.001).

GENDER-Q Scars

Of the 12 hypotheses assessed for the GENDER-Q Scars scale, none were rejected, resulting in an acceptance rate of 100% (Table 3).

Group-level differences for the Scars scale are shown in Table S2. As hypothesized, Scars scale scores varied by revision status. Participants who had undergone surgery and needed revisions at survey completion reported the lowest scores (56.6(20.3)), followed by those who had undergone surgery and underwent revisions (71.1(23.5), P < 0.001), and those who had undergone surgery and did not need revisions reported the highest scores (84.0(15.9), P < 0.001) (Fig. 1c). The hypothesis was confirmed that participants who underwent periareolar mastectomies had higher satisfaction with scars compared with participants who underwent double incision mastectomies (P < 0.001). Regarding complications and revisions, participants who needed future revisions for hypopigmentation or scars scored lower than those who had a revision or did not need revisions, as hypothesized (P < 0.001).

Correlations between the Scars scale and other GENDER-Q scales are shown in Table S3. All scales correlated as hypothesized. The Chest and Nipples & Areolas scales were considered related but dissimilar constructs to the Scars scale (r = 0.3 to <0.5, P < 0.001) and all other correlations were considered dissimilar constructs to the Scars scale (r < 0.3, P < 0.001).

Discussion

The GENDER-Q is a comprehensive PROM developed by an international team of experts in collaboration with TGD individuals to rigorously measure PROs across the spectrum of gender-affirming care, including surgery^6,20–22. The GENDER-Q Chest, Nipples & Areolas, and Scars scales were specifically designed to measure chest appearance in masculinizing gender-affirming chest surgery. In this psychometric analysis guided by COSMIN^29–31, the GENDER-Q Chest scales demonstrated construct validity for assessing the appearance of the chest, nipples and areolas, and scars. Participants who had undergone surgery reported higher satisfaction compared with those who wanted to but had not yet undergone surgery. These findings show that the GENDER-Q Chest scales can generate high-quality, patient-centred data regarding the impact of masculinizing gender-affirming chest surgery. Collecting this evidence is crucial given the current heightened interest in understanding outcomes of gender-affirming care, as such information can inform clinical care, quality improvement, and policy decisions.

Through confirmation of most a priori hypotheses, the present study provides evidence of construct validity for the GENDER-Q Chest scales, which were specifically developed for TGD individuals undergoing masculinizing gender-affirming chest surgery. Establishing construct validity is essential to ensuring that an instrument accurately measures its intended concept, thereby strengthening its clinical utility^23,24. This work builds on the previously reported psychometric properties for the GENDER-Q Chest scales (Table S1)²². Structural validity of all three scales was supported by Rasch Measurement Theory (RMT) analysis, which demonstrated overall model fit, one-dimensionality, and acceptable item performance. The Person Separation Index (PSI) values ranged from 0.81 to 0.95, indicating adequate to excellent measurement precision. Reliability was further supported by Cronbach α coefficients (0.92–0.99) and intraclass correlation coefficients (0.93–0.96), demonstrating strong internal consistency and test-retest reliability. No differential item functioning by age was detected for any scale, indicating stable performance across age groups. The smallest detectable change ranged from 1.0 to 1.1 points across the scales.

Furthermore, by involving TGD communities throughout the development of these scales, the GENDER-Q not only accurately measures relevant constructs but also uses TGD-inclusive language and reflects patient priorities³³, making it a meaningful tool for research in this field. This participatory approach improves data accuracy, strengthens trust between participants and researchers, and enhances the credibility of data generated by these instruments^34,35.

In this study, participants who had undergone surgery and did not need revisions at survey completion reported the highest satisfaction on the GENDER-Q Chest and Nipples & Areolas scales, followed by those who had undergone surgery and needed revisions at survey completion, while participants who wanted to undergo surgery but had not yet undergone surgery reported the lowest satisfaction. These findings suggest that masculinizing gender-affirming chest surgery is efficacious in improving chest appearance satisfaction for individuals who desire these procedures, consistent with previous research demonstrating the far-reaching benefits of masculinizing gender-affirming chest surgery^8–15. Prior studies have used instruments such as the Transgender Congruence Scale (TCS), Gender Congruence and Life Satisfaction (GCLS) scale, Chest Dysphoria Scale (CDS), Body Image Quality of Life Index (BIQLI), BREAST-Q, and BODY-Q Chest and Nipples scales (Table S4)^8–12,15. The TCS, GCLS, and CDS are the only instruments that were developed exclusively among TGD individuals; however, the TCS and GCLS assess appearance generally, rather than surgical outcomes, and the CDS lacks robust development and psychometric validation^10,36,37. The BIQLI and BREAST-Q were developed for cisfemales and may lack content validity for TGD individuals^38,39. While previous studies using the BREAST-Q have shown significant benefits after masculinizing gender-affirming chest surgery⁹, it was not developed for TGD individuals undergoing chest masculinization and many questions are not applicable to TGD individuals (for example questions about wearing a bra). Therefore, these measures may not accurately reflect the aspects of satisfaction and quality of life most important to TGD individuals, so the results should be interpreted with caution. The BODY-Q Chest and Nipples scales were developed and validated in TGD individuals undergoing masculinizing gender-affirming chest surgery^40,41 and have been widely used to measure chest appearance satisfaction in this population^{11,12,15,42,43}. Even so, because these scales were also designed for cisgender individuals undergoing body contouring and gynaecomastia procedures, they lack questions that were added to the GENDER-Q to maximize content validity in masculinizing gender-affirming chest surgery^40,41. Furthermore, the GENDER-Q Chest and Nipples & Areolas scales use six response options per item, compared with four in the BODY-Q Chest and Nipple scales, allowing for greater precision and discrimination of nuanced patient experiences. Given these advantages, the GENDER-Q Chest and Nipples & Areolas scales are recommended over the BODY-Q Chest and Nipple scales for assessing PROs in masculinizing gender-affirming chest surgery.

This study has limitations. Given the various recruitment techniques that were used, including the use of community outreach and social media platforms, the total number of individuals reached is unable to be determined and thus the participation rate cannot be estimated. Reliance on self-reported, online data collection may exclude individuals with limited technology access or those living in unsafe environments. The survey length could also result in decreased participation due to time constraints or fatigue. Accordingly, selection and non-response bias are possible. For example, people who previously experienced discrimination when seeking gender-affirming care may have been less likely to participate, whereas those with strong opinions or greater technological proficiency may have been more motivated to complete the survey. As such, these dynamics could bias estimates in either direction. The predominantly White sample from mostly North America and Europe limits the generalizability to individuals of differing racial or ethnic backgrounds and geographical regions. Cultural differences may influence how individuals engage with PROMs, including how questions are understood, which outcomes are prioritized, comfort with sensitive topics, and the response burden of completing multiple instruments⁴⁴. Further validation in geographically, racially, and ethnically diverse samples would broaden applicability and support cross-cultural adaptation of the GENDER-Q scales. Nonetheless, the large, international sample of greater than 2800 participants strengthens the credibility of these findings and enhances the statistical power of the analyses. Lastly, recall bias may affect responses about surgical history, such as type of surgery or complications; however, this does not impact GENDER-Q Chest scales’ scores, as these scales assess the participants’ current perception of their appearance.

These findings have several important implications for advancing the study of masculinizing gender-affirming chest surgery. The GENDER-Q Chest scales now enable researchers to generate high-quality, longitudinal evidence regarding outcomes most important to patients. Collecting this data can empower patients to make evidence-informed decisions and allow clinicians to adapt their practices accordingly based on the long-term outcomes after this surgery. For policymakers, data generated from the GENDER-Q Chest scales can also inform decisions regarding policy, reimbursement models, and advocacy efforts regarding masculinizing gender-affirming chest surgery. Determining the GENDER-Q Chest scales’ responsiveness, minimally important differences, and normative values would be valuable future work to enhance the interpretability of data generated from these scales^45–47.

Evaluating the outcomes in masculinizing gender-affirming chest surgery is critical given the growing demand for high-quality research in this field. The GENDER-Q was rigorously developed to address the lack of validated PROMs in gender-affirming surgery. This study extends the psychometric assessment of the GENDER-Q Chest, Nipples & Areolas, and Scars scales and provides additional support for their construct validity. The findings demonstrate that the GENDER-Q Chest scales are effective measures of chest, nipple, and scar appearance in masculinizing gender-affirming chest surgery and can be used to generate high-quality evidence on the impact of these procedures on patients’ lives.

Funding

Funding was provided by grant 167288 from the Canadian Institutes of Health Research (CIHR) (M.N.K./A.L.P./A.F.K.). The funder had no role in: the design and conduct of the study; the collection, management, analysis, and interpretation of the data; the preparation, review, or approval of the manuscript; and the decision to submit the manuscript for publication. No other authors have relevant sources of funding to disclose.

Author contributions

Caleb Haley (Formal analysis, Investigation, Visualization, Writing—original draft, Writing—review & editing), Shane D. Morrison (Conceptualization, Formal analysis, Investigation, Methodology, Writing—original draft, Writing—review & editing), Manraj N. Kaur (Conceptualization, Formal analysis, Investigation, Methodology, Writing—review & editing), Charlene Rae (Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Writing—original draft, Writing—review & editing), Megan Lane (Investigation, Writing—review & editing), Danny A Young-Afat (Investigation, Writing—review & editing), Tim C. van de Grift (Investigation, Writing—review & editing), Nicola R. Dean (Investigation, Writing—review & editing), Kathleen A. Armstrong (Investigation, Writing—review & editing), Devin Coon (Investigation, Writing—review & editing), Zac A. Cannell (Investigation, Writing—review & editing), Christian X. Lava (Investigation, Writing—review & editing), Sylvie D. Cornacchi (Conceptualization, Data curation, Investigation, Project administration, Resources, Writing—review & editing), Alexis Laungani (Investigation, Writing—review & editing), Margriet G Mullender (Investigation, Writing—review & editing), Jens A. Sørensen (Investigation, Writing—review & editing), Lotte Poulsen (Investigation, Writing—review & editing), Jack G. Graesser (Investigation, Writing—review & editing), Thomas Satterwhite (Investigation, Writing—review & editing), Allison C. Hu (Investigation, Writing—review & editing), Gerhard S. Mundinger (Investigation, Writing—review & editing), Hilliard T. Brydges (Investigation, Writing—review & editing), Jessica J. Hsu (Investigation, Writing—review & editing), Blair R. Peters (Investigation, Writing—review & editing), Jens U. Berli (Investigation, Writing—review & editing), Christodoulos Kaoutzanis (Investigation, Writing—review & editing), Nargis Kalia (Investigation, Writing—review & editing), Rachel Bluebond-Langler (Investigation, Writing—review & editing), Oren Ganor (Investigation, Writing—review & editing), Alireza Hamidian Jahromi (Investigation, Writing—review & editing), Bashar A. Hassan (Investigation, Writing—review & editing), Fan Liang (Investigation, Writing—review & editing), John H. Pang (Investigation, Writing—review & editing), Edward C. Ray (Investigation, Writing—review & editing), Gabriel A. Del Corral (Investigation, Writing—review & editing), Kenneth L. Fan (Investigation, Writing—review & editing), Lily R. Mundy (Investigation, Writing—review & editing), Andrea L. Pusic (Conceptualization, Investigation, Methodology, Supervision, Writing—review & editing), and Anne F. Klassen (Conceptualization, Formal analysis, Funding acquisition, Investigation, Methodology, Supervision, Writing—review & editing)

Disclosure

M.N.K., A.L.P., and A.F.K. reported being codevelopers of the GENDER-Q instrument, which is owned by McMaster University and Mass General Brigham, and receiving a share of license revenues as royalties for its use in for-profit research based on their institutions’ inventor sharing policies. C.H. reported previously received funding from the National Institutes of Health (NIH)—grant T32 HS000053. M.N.K., A.L.P., and A.F.K. reported receiving grants from the Canadian Institutes of Health Research during the conduct of the study. C.R. reported receiving grants from the Canadian Institutes of Health Research during the conduct of the study. J.U.B. reported owning Jens Berli Consulting and providing expert legal counsel and educational consulting to Johnson & Johnson and other groups outside the submitted work. K.L.F. reported consulting for Integra outside the submitted work. A.F.K. reported consulting for Anne F Klassen Research through EVENTUM Research outside the submitted work. The authors declare no other conflict of interest.

Supplementary material

Supplementary material is available at BJS online.

Data availability

Given the personal nature of the data, data will not be publicly available to protect the study participants from the potential risk of identification. Individuals may request access to the data or the analysis code by contacting the corresponding author. Decisions will be made on a case-by-case basis based on the reason for the request.