Primary Breast Augmentation Clinical Trial Outcomes Stratified by Surgical Incision, Anatomical Placement and Implant Device

Namnoum, James

Goals/Purpose: This study assesses the relative risk of select adverse events stratified by surgical incision, anatomical pocket and breast implant device in primary augmentation patients enrolled in long-term clinical trials

Methods/Technique:

Relative risk (RR) for time-to-first-event of capsular contracture, moderate-severe malposition, and secondary procedure were calculated using time-to-event regression analysis in the primary augmentation cohorts (4,412 patients; 8,811 implants)of the Core (NCT00689871) and 410 (NCT00690339) clinical trials.

Results/Complications:

The risk of capsular contracture (adjusted model) was significantly increased with axillary versus inframammary incision [RR: 2.39 (95% CI: 1.43, 3.99), p<0.001]. The risk of capsular contracture was significantly reduced with submuscular versus subglandular placement [RR: 0.43 (95% CI: 0.33, 0.56), p<0.001], textured surface/round/silicone-filled devices [RR: 0.64 (95% CI: 0.42, 0.96), p<0.05], and textured surface/shaped/highly cohesive silicone-filled devices [RR: 0.49 (95% CI: 0.34, 0.70), p<0.001], versus smooth surface/round/silicone-filled devices. Risk of capsular contracture stratified by anatomical placement is presented in the Table. The risk of moderate-severe malposition (adjusted model) was significantly increased with axillary [RR: 3.97 (95% CI: 1.84, 8.58), p<0.001] and periareolar [RR: 1.67 (95% CI: 1.07, 2.60), p<0.05] versus inframammary incision, and significantly reduced with submuscular versus subglandular placement [RR: 0.64 (95% CI: 0.43, 0.97), p<0.05]. The risk of secondary procedures (adjusted model) was significantly increased with axillary [RR: 1.76 (95% CI: 1.19, 2.60), p<0.001] and periareolar [RR: 1.45 (95% CI: 1.19, 1.78), p<0.001] versus inframammary incision.

Table: Combined Core and 410 Studies Primary Augmentation Cohorts: Risk of Capsular Contracture, Moderate-Severe Malposition, and Secondary Procedure Due to Adverse Event

	Capsular Contracture (Baker Grade 3-4)¹		Capsular Contracture: Subglandular²		Capsular Contracture: Submuscular³		Malposition (Moderate-Severe)⁴		Secondary Procedure Due to Adverse Event⁵
	Unadjusted RR (95% CI)	Adjusted RR⁶ (95% CI)	Unadjusted RR (95% CI)	Adjusted RR⁶ (95% CI)	Unadjusted RR (95% CI)	Adjusted RR⁶ (95% CI)	Unadjusted RR (95% CI)	Adjusted RR⁶ (95% CI)	Unadjusted RR (95% CI)	Adjusted RR⁶ (95% CI)
Patient age at surgery, continuous (yrs)	1.02 (1.01, 1.04)†	1.02 (1.01, 1.04)**	1.00 (0.98, 1.02)	1.00 (0.98, 1.02)	1.03 (1.02, 1.05)†	1.03 (1.02, 1.05)†	1.00 (0.98, 1.02)	1.00 (0.98, 1.02)	1.01 (1.00, 1.02)	1.01 (1.00, 1.02)
Incision site
Inframammary	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref
Periareolar	1.90 (1.46, 2.48)†	1.35 (1.00, 1.82)	1.93 (1.27, 2.95)**	1.34 (0.81, 2.20)	1.81 (1.29, 2.54)†	1.38 (0.92, 2.06)	1.81 (1.22, 2.69)**	1.67 (1.07, 2.60)*	1.47 (1.23, 1.76)†	1.45 (1.19, 1.78)†
Axillary	3.00 (1.91, 4.69)†	2.39 (1.43, 3.99)†	1.25 (0.31, 5.13)	0.87 (0.19, 3.96)	3.62 (2.19, 6.00)†	2.65 (1.40, 5.02)**	3.69 (1.91, 7.10)†	3.97 (1.84, 8.58)†	1.91 (1.36, 2.69)†	1.76 (1.19, 2.60)†
Surgical pocket
Subglandular	Ref	Ref	—	—	—	—	Ref	Ref	Ref	Ref
Submuscular	0.39 (0.31, 0.50)†	0.43 (0.33, 0.56)†	—	—	—	—	0.68 (0.46, 1.00)*	0.64 (0.43, 0.97)*	0.85 (0.71, 1.02)	0.90 (0.74, 1.09)
Device type
Smooth/round/silicone	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref
Textured/round/silicone	0.77 (0.54, 1.11)	0.64 (0.42, 0.96)*	0.38 (0.22, 0.65)†	0.39 (0.20, 0.74)**	0.95 (0.58, 1.56)	0.83 (0.47, 1.45)	0.84 (0.44, 1.59)	1.02 (0.50, 2.08)	1.22 (0.93, 1.60)	1.23 (0.90, 1.66)
Textured/shaped/highly cohesive silicone	0.35 (0.27, 0.46)†	0.49 (0.34, 0.70)†	0.32 (0.20, 0.52)†	0.39 (0.21, 0.73)**	0.40 (0.28, 0.57)†	0.53 (0.33, 0.86)**	0.49 (0.32, 0.77)**	0.91 (0.52, 1.60)	0.80 (0.64, 0.99)*	0.98 (0.75, 1.27)

RR: relative risk; CI: confidence interval; Ref: Reference group; *p<0.05; **p<0.01; †p<0.001.

¹N=317 events of capsular contracture, Baker grade 3-4.

²N=104 events of capsular contracture in subglandular position.

³N=209 events of capsular contracture in submuscular position.

⁴N=156 events of moderate-severe malposition.

⁵N=774 events of secondary procedure due to adverse event.

⁶Multivariate models adjusted for variables in the table in addition to device volume, parenteral antibiotics, parenteral steroids, pocket irrigation with antibiotics, pocket irrigation with betadine, and use of drains.

Conclusion:

In patients undergoing primary breast augmentation, surgical incision and anatomical pocket, and device type were significant ptrdictors of clinical outcomes. A textured surface/ highly cohesive gel device was associated with a significantly reduced risk of capsular contracture, independent of anatomical plane.