Study 1: This was a RCT comparing scar cosmesis between 5-0 polypropylene (PP) sutures and 5-0 fast absorbing plain gut (FG) during layered repair of linear cutaneous surgery wounds. The study design used a split-wound, within person design. Inclusion criteria included: >18 y/o, scheduled for cutaneous surgical procedure with predictive linear closure, and willingness to return for follow-up visits. Exclusion criteria included mental impairment, unable to consent, unable to understand English, incarceration, pregnant, and wounds <3 cm. Wounds were divided into half and equal amounts of sutures were placed on each side in a similar fashion with randomization of material. PP sutures were removed in 5-7 days or 10-14 days depending on the location. Patients were seen 3 months after the procedure for follow up. Two blinded physicians used a patient observer scar assessment scale (POSAS) and the sum of the average of the scores was the primary outcome measure. Secondary outcome was the sum of the patient component score of the POSAS scale. Paired t-test was used for POSAS scores. A minimal meaningful difference of 3 points was chosen based upon consensus among authors. 88% of patients returned for follow up. For the primary outcome using two blinded physicians, PP POSAS vs FG was 10.26 vs 12.74,  p <0.001. The mean sum of patient assessed components of POSAS  was PP 12.3 vs FG 14.34 , p=0.11. Though a statistically significant difference was achieved for the primary outcome, the difference was just below the threshold for what was considered a “minimal meaningful clinical difference” in the studies power calculation.

Study 2: This was a RCT comparing cosmetic outcomes of facial lacerations (1-5 cm) in pediatric patients repaired using fast-absorbing catgut (FAC) vs nylon (NYL) sutures. A non inferiority design was applied using a 100-mm visual analog scale (VAS) with a difference <15 mm set for noninferiority (determined based on previous studies). VAS scores were calculated by 3 blinded physicians (averaged to one score) and also caregivers. The primary outcome of this study was to compare physician VAS scores. Secondary objectives included caregivers VAS scores. Inclusion criteria included: English speaking 1-18 y/o, isolated, non contaminated linear facial lacerations 1-5cm in length. Exclusion criteria:  <1 cm or >5 cm facial laceration, irregular borders, mammalian bites, contaminated, >8 hours old, or could be repaired with topical tissue adhesives. Complex lacerations requiring repair by surgical specialists and those with bleeding disorders, diabetes, allergic reactions to topical anesthetics, pregnancy, and renal dysfunction were also excluded. Lacerations were then repaired with either 5-0 FAC or 5-0 NYL. Patients were seen for follow-up in 4-7 days and nonabsorbable sutures were removed at this point. Patients then followed up in 3-4 months, chosen by the FDAs determination that laceration repair cosmetic outcome is best evaluated at 3 months. Photographs of wounds were taken and then evaluated using a VAS by 3 PEM physicians who were blinded. VAS scores were 100-mm with the best scar at 100 and worst at 0. Caregivers were also asked to complete a VAS. Student t test was used to analyze the results. 98 total patients were enrolled. 22 patients were lost to follow-up along with other study design complications such as the death of the PI and loss of data. 29 patients ended up in the FAC group and 32 in NYL with regards to the primary outcome of VAS score. The mean VAS scores for physicians for FAC vs NYL was 57.6 and 67.6, (∆ -10.0, 95% CI of -19.1 to -0.4). This difference of -10 between groups had a lower bound of the CI (-19.1) that was less than the NI margin of -15mm, thus NI could not be established for FAC with regards to physician VAS. Mean caregiver VAS scores for FAC and NYL were 93.8 and 86.6, (∆ 7.2, 95% CI of -4.9 to 13.9). The lower bound of the CI (-4.9) was greater than the NI margin of -15mm, thus noninferiority was established for caregiver VAS. 

Conclusions: Based on my review of the literature, I would ultimately choose to use non-absorbable sutures given this limited data showing a more favorable cosmetic outcome from a physician perspective, however with a low threshold to use absorbable in certain patient populations that this cosmetic benefit of non-absorbable sutures might be compromised (agitated patients/children, limited follow up, poor wound care etc).

References: 

1. Eisen DB, Zhuang AR, Hasan A, Sharon VR, Bang H, Crispin MK. 5-0 Polypropylene versus 5-0 fast absorbing plain gut for cutaneous wound closure: a randomized evaluator blind trial. Arch Dermatol Res. 2020 Apr;312(3):179-185. doi: 10.1007/s00403-019-02009-5. 

2. Luck R, Tredway T, Gerard J, Eyal D, Krug L, Flood R. Comparison of cosmetic outcomes of absorbable versus nonabsorbable sutures in pediatric facial lacerations. Pediatr Emerg Care. 2013 Jun;29(6):691-5. doi: 10.1097/PEC.0b013e3182948f26. PMID: 23714755.​