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Onishi et al. Plast Aesthet Res 2024;11:5 https://dx.doi.org/10.20517/2347-9264.2023.102 Page 3 of 10

- Remedial exercise: All patients participated in exercises to stimulate lymph drainage.

- Manual lymph drainage: Massage was performed by trained therapists to aid drainage.

After discharge, patients continued wearing compression garments and performing self-massage and
exercises at home. They were followed up at 1 week, 1 month, 3 months, 6 months, and 12 months
postoperatively to monitor limb volume and receive additional CDT as needed.

Surgical indication
1. Edema plateaued and remained despite reduction by proper CDT

2. Subjective symptoms such as heaviness, fatigue, and tightness remained despite proper CDT

3. Intolerance of CDT due to physical or mental difficulties

Surgical procedure
Prior to surgery, ICG lymphangiography was performed to visualize the lymphatic drainage pattern and
plan the anastomotic sites, usually three sites [Figure 1]. Patent blue was additionally used in a subset of
patients whose lymphatic vessels were anticipated to be challenging to identify under the surgical
microscope with ICG alone. The collective lymphatic vessels and subcutaneous veins were located after skin
incisions at each of the three surgical sites. The lymphatic and subcutaneous veins were anastomosed in a
side-to-end fashion, where a side-wall incision was made on a lymphatic vessel to join it to a nearby
subcutaneous vein using 11-0 nylon sutures under a surgical microscope.

Data collection
We collected clinical data, including age, body mass index (BMI), number of irradiated areas, previous
chemotherapy (taxane), previous LVA, clinical stage, history of lymphangitis, the period from onset of
lymphedema to CDT, duration of CDT before LVA surgery, compression class of the elastic garment, and
measured girth. The clinical stage was based on the classification of lymphedematous limbs set forth by the
International Society of Lymphology. Girth measurements were performed at five points on the upper
extremities: hand (C ), wrist (C ), forearm (C), elbow (C ), and upper arm (C ). Girth measurement data
f
e
w
h
a
were collected at the first visit, one month before, and one year after LVA surgery. Extremity volume was
estimated using the upper extremity lymphedema index (UEL index) which is given by the formula: UEL
[6]
2
2
2
index = (C + C + C + C + C )/BMI. PEV was defined as the percentage difference between the UEL
2
2
w
h
e
f
a
index of the affected and healthy limbs.
Statistical analysis
Overlap weighting is a propensity scoring method that aims to mimic important attributes of randomized
clinical trials, such as a clinically relevant target population, covariate balance, and precision. We applied
overlap weighting to adjust for confounding factors and improve the robustness of our findings. We
estimated propensity scores (PS) using logistic regression and calculated the overlap weights for each
participant based on their propensity scores. The propensity score was calculated using a logistic regression
model with the following variables: age, BMI, number of irradiated areas, previous chemotherapy (taxane),
previous LVA, history of lymphangitis, duration from the onset of lymphedema to CDT, PEV at the first
visit, and compression classes of compression garments during the preoperative CDT period. Overlap
weights were computed as 1-PSi when participant i is from the target population, otherwise, PSi. After
applying overlap weighting, we compared the PEV at 1 year postoperatively and the reduction rate between
the early and non-early indication groups.