Striae Distensae: A Comprehensive Review and Evidence-Based Evaluation of Prophylaxis and Treatment

S. Al-Himdani; S. Ud-Din; S. Gilmore; A. Bayat

The British Journal of Dermatology. 2014;170(3):527-547.

Abstract and Introduction

Abstract

Striae distensae are an extremely common, therapeutically challenging form of dermal scarring. Risk factors have been reported but much remains to be understood about their epidemiology, diagnosis and treatment. Up-to-date knowledge of the scientific research and the evidence behind both preventative and therapeutic agents are vital in order to understand striae and to offer patients the best therapeutic alternatives. We present a clinical review of the current literature concerning striae distensae and their prevention and treatment. A systematic review of the literature was undertaken using Medline, Embase and Google Scholar. Articles in English, Spanish, Portuguese, Turkish and French were included. Striae distensae occur in pregnancy, puberty and obesity as well as in numerous medical conditions and following therapeutic interventions. Proposed aetiological mechanisms relate to hormones, physical stretch and structural alterations to the integument. Assessment methods include subjective visual scoring and various imaging modalities. Treatments that we have evaluated include topical agents, used prophylactically or therapeutically, as well as light and laser therapies, which have shown improvements in the appearance of striae. Few high level evidence based medicine randomized controlled trials evaluating treatments for striae distensae exist. Topical therapeutic agents appear to lack efficacy in the prevention of striae distensae.

Introduction

Striae distensae (SD; striae, stretch marks, striae atrophicans, striae gravidarum) are common skin lesions, which can pose a significant psychological burden for patients. Since the first histological description in 1889,^[1] SD have presented a considerable challenge in terms of both their evaluation and treatment. Although frequently encountered by both patients and clinicians, the prevalence of SD cited in the literature varies tremendously, ranging from 11% to 88%.^[2–10] Additionally, anatomical sites affected vary, with areas commonly affected including the abdomen, breasts, thighs and buttocks.^[2,3]

Two clinically and histopathologically recognizable forms of SD have been described: striae rubrae and striae albae.^[11] The initial erythematous and violaceous-appearing lesions are referred to as striae rubrae. These fade into wrinkled, hypopigmented, atrophic scar-like marks named striae albae, which have been described as a permanent form of SD.^[12] When occurring following pregnancy, the term striae gravidarum refers to the same entity, usually developing after the 24th week of gestation.^[8,13] Although the vast majority of SD have been reported in pregnant women and adolescents,^[6,13] they have also been described in association with Cushing syndrome and following the administration of both short- and long-term oral and topical corticosteroids.^[13,14,15] Further to this, a number of key aetiological theories have been postulated. These include inadequate development of the skin (particularly elastic fibres and collagen),^[16,17] mechanical stretching of the skin and endocrine imbalance.^[18,19]

Several methods of assessing SD, visually or instrumentally, have been utilized in previous studies.^[9,20] Here we present a comprehensive review of the literature, incorporating articles from multiple search engines and languages. We focus on the epidemiology, aetiology, clinical evaluation, prevention and treatment of SD.

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Abstract and Introduction
Methods
Results
Conclusions
References
Sidebar

Table 1. Levels of evidence (LOE).
LOE-1	Systematic review with homogeneity of RCTs
LOE-2	Systematic review with homogeneity of cohort studies
	RCT
	Cohort study
	'Outcomes' research; ecological studies
LOE-3	Systematic review with homogeneity of case–control studies
	Nonrandomized controlled trial
	Individual case–control study
LOE-4	Case series
LOE-4	Comparative study
LOE-5	Case reports
LOE-5	Expert opinion without critical appraisal/based on physiology/bench research or 'first principles'

RCT, randomized controlled trial. Adapted from Oxford Centre of Evidence-Based Medicine.²¹

Table 2. Comparison of striae distensae among different patient population groups. ^{2-8,10,15,20,24-29}
Patient group	Location (most common to least common)	Proposed mechanism of formation	Average age (years)	Approximate prevalence (%)
Adult pregnant women	Abdomen, breasts, thighs	Stretch due to increased abdominal girth, adrenal cortical hyperactivity	23–27	43–88
Adult nonpregnant women	Breasts and thighs	Postpregnancy	29	35
Adolescent females	Thighs, buttocks, breasts	Stretching of the skin during growth spurt, adrenocortical hyperactivity	13–14	72–77
Adolescent males	Buttocks, thighs, calves, back	Stretching of the skin during growth spurt, adrenocortical hyperactivity	14	6–86
Adult males	Buttocks	Sudden weight gain/loss, muscular exercise	ND	11

ND, No data in the literature.

Table 3. Constitutional and pregnancy-related factors associated with striae distensae.
Factor	Davey (1972)⁹	Murphy et al. (1992)²⁸	Chang et al. (2004)⁶	Thomas and Liston (2004)⁵	Atwal et al. (2006)²⁰	Osman et al. (2007)⁸	Ghasemi et al. (2007)⁷	Maia et al. (2009)²⁵	Canpolat et al. (2010)²⁴
Constitutional
Maternal age		+		+		+		+	+
Maternal BMI		+		+	+		+		+
Maternal weight	+
Thickness of abdominal skin fold	+
Positive family history			+						+
Smoker								+
Use of cream	+
Pregnancy related
Birthweight	+	+				+	+	+	+
Gestational age									+
Weight gained during pregnancy					+	+		+
Polyhydramnios									+

BMI, body mass index; +, statistically significant.

Table 4. Medical conditions, surgery, medications and other factors linked with striae distensae. ^{2,9,13,14,33-52}
Associations with striae distensae
Medical conditions
Marfan syndrome, Cushing syndrome, anorexia nervosa, typhoid fever, rheumatic fever, chronic liver disease, obesity
Surgery
Augmentation mammoplasty, tissue expanded skin, tension-requiring skin sutures, organ transplantation, cardiac surgery
Medications
Systemic and topical corticosteroids, HIV therapy, chemotherapy, tuberculosis therapy, contraceptives, neuroleptics
Other
Pregnancy, puberty, stretch and weight training, idiopathic

HIV, human immunodeficiency virus.

Table 5. Histological comparisons of striae rubrae and striae albae ^{17,18,64–67}
	Striae rubrae	Striae albae
Clinical appearance	Raised pink linear lesions	Pale, depressed and finely wrinkled lesions; appear similar to scars
Epidermis	Oedema between melanocytes and keratinocytes; increased melanogenesis	Epidermal atrophy, loss of rete ridges and absent hair follicles; reduction in melanocytes leading to leucoderma
Papillary dermis	Vascular ectasia and possible angiogenesis	Lack of vascular stimulation
Reticular dermis	Collagen fibres structurally altered; elastic fibres reduced and reorganized; fine elastic fibres predominate throughout dermis with thick, tortuous fibres toward the periphery; reduced fibrillin microfibrils at the dermal–epidermal junction	Densely packed collagen parallel to skin surface; predominantly thick elastic fibres in dermis with normal appearance in periphery
Inflammatory cells	Dermal oedema, cuffing of the small vessels by lymphocytes, absent mast cells and prominent fibroblasts; increased glycosaminoglycan content	Eosinophils predominate among collagen fibres

Table 6. Visual and imaging techniques used to assess type, severity and efficacy of treatments of striae distensae (SD). ^{7,9,20,64,65,74-78}
Method	Type of striae	Explanation of method
Davey method	Striae rubrae and albae	Abdominal SD. Abdomen divided into quadrants using midline vertical and horizontal lines through umbilicus as divisions. Each quadrant given a score (0, no SD; 1, moderate number of SD; 2, many SD). Score is given out of 8
Atwal score	Striae rubrae and albae	Maximum score of six for each site (abdomen, hips, breasts, thigh/buttocks). Score 0–3 for presence of striae (0, no SD; 1, < 5 SD; 2, 5–10 SD; 3, > 10 SD); score 0–3 for presence of erythema (0, no erythema; 1, light red/pink; 2, dark red; 3, purple). Score out of 24
Dermoscopy	Striae rubrae, caerulae, nigrae and albae	Visualization of melanin networks and distinction of different types of striae due to the differences in melanin pigmentation: striae rubrae demonstrate a hypermelanosis while striae albae demonstrate leucoderma secondary to reduced melanocytes
Epiluminenscence colorimetry	Striae rubrae, caerulae, nigrae and albae	Computer device that measures colour from observer-defined small areas in photographs
Reflectance confocal microscopy	Striae rubrae and albae	Used in vivo. Low-power infrared laser reflects light from a single in-focus plane at different levels of depth in the skin. Readily visualizes the collagen and elastic fibre architecture and may be used to monitor treatment efficacy. SD appear more anisotropic and have greater skin roughness than adjacent skin. Not useful in evaluating inflammatory changes in striae formation
Primos 3D camera	Striae rubrae and albae	Reflected light absorbed by a high-resolution camera that records height differences from which a 3D image is produced. 3D image demonstrates the skin-surface topography including the depth, distribution and variation of skin furrows

Table 7. Summary and levels of evidence for topical treatments used in the treatment of striae distensae (SD).
Author	Treatment evaluated	Form of treatment	Striae type	Dosage	No. of subjects (T/C)	Outcome	Adverse effects	Study design	Level of evidence
Kang et al.[12, 80]	Tretinoin vs. placebo	Therapeutic	Rubrae	0·1% daily, 6 months	22 (10/12)	80% (n = 8) of tretinoin-treated patients had definite marked improvement, compared with 8% (n = 1) in control group. Reduced length and width of striae by 14% and 8%, respectively, compared with increased length and width in control by 10% and 24%, respectively. No significant difference in dermal collagen and elastic fibres in treatment compared with placebo	Erythema or scaling first 2 months (55%)	RCT	2
Rangel et al.⁸¹	Tretinoin	Therapeutic	Not stated	0·1% daily, 3 months	20	Reduction in length of stretch marks by up to 20%. Significant global improvement from baseline noted in all stretch marks. Half of the abdomen was treated and the other half acted as the control. No randomization in this study	Erythema or scaling in first month (55%)	Nonrandomized controlled trial	3
Mallol et al.⁷³	Trofolastin (Centella asiatica ) vs. placebo	Prophylaxis	Not stated	Daily, 12th week pregnancy until labour	80 (41/39)	Results demonstrated that 56% in placebo and 34% in treated group developed striae. The arbitrary score (from 0–3) for intensity was 1·42 for the treated group and 2·13 for the placebo group. In women with a history of SD during puberty, the treatment cream gave a significant absolute prevention of SD of 89%	None stated	RCT	2
Ud-Din et al.⁸²	Silicone vs. placebo either side of abdomen	Therapeutic	Not stated	Daily for 6 weeks	20	Results demonstrated increased melanin, with decreased haemoglobin, collagen and pliability on both sides. Collagen levels were significantly higher and melanin lower with silicone gel compared with controls	None stated	RCT	2
Draelos et al.⁸³	Centella asiatica/hyaluronic acid	Therapeutic	Rubrae	Twice daily, 12 weeks	52	Statistically significant difference in participant and investigator evaluations of overall appearance, colour, softness and texture between treatment and control groups. Patient's untreated thigh acted as control. No placebo used	None stated	RCT	2
Wierrani et al.⁸⁴	Verum® (hyaluronic acid)	Prophylaxis	Not stated	Unknown	50 (24/26)	One-third of women with prophylactic treatment developed SD compared with two-thirds in the control group. Better results in those women that were not overweight. Unclear risk of attrition and performance bias	None stated	RCT	2
de Buman et al.⁸⁵	Alphastria® vs. placebo	Prophylaxis	Not stated	Unknown	90 (30/30/30)	Three groups: A = Alphastria cream, B = cream with excipients and vitamins, C = placebo with just excipient. 10% in prophylactically treated compared with 70% in placebo treated developed striae	None stated	RCT	2
Osman et al.⁸⁶	Cocoa butter vs. placebo	Prophylaxis	Not stated	Daily, 12–18 weeks' gestation until delivery	175 (91/84)	No significant difference in development of SD between treatment and placebo groups	None stated	RCT	2
Buchanan et al.¹⁹	Cocoa butter vs. placebo	Prophylaxis	Not stated	Daily, 12–15 weeks' gestation until delivery	300 (150/150)	No significant difference in development of striae between treatment and placebo groups	None stated	RCT	2
Taavoni et al.⁸⁷	Olive oil	Prophylaxis	Not stated	Twice daily, 18–20 weeks' gestation, for 8 weeks	70 (35/35)	Subjects randomized into control or intervention group. Intervention group applied olive oil and control group underwent no intervention. No significant difference in development of SD between treatment and control groups. No placebo used for control group	None stated	RCT	2
Timur and Kafkasli⁸⁸	Almond oil with massage vs. almond oil alone vs. control	Prophylaxis	Not stated	Cream every other day, 19th–32nd week gestation	141 (47/48/46)	Significant difference in frequency of SD between groups: almond oil and massage 20%, almond oil alone 38·8%, control 41·2%	None stated	Nonrandomized controlled trial	3
Mendez et al.⁸⁹	Hydrant cream wet skin vs. hydrant cream dry skin	Prophylaxis	Not stated	Daily, 16–18 weeks' gestation until delivery	50	Percentage of women without SD was 57% when cream applied on wet skin compared with 44% when applied to dry skin. Skin on the patients forearm acted as a control.	None stated	RCT	2
Ash et al.⁹⁰	20% glycolic acid/10% ascorbic acid/2% zinc sulfate/0·5% tyrosine vs. 20% glycolic acid/0·05% tretinoin. Applied onto SD on abdomen or thighs with area split into halves	Therapeutic	Albae	Daily, 12 weeks	10	Both regimens improved appearance of SD. They both increased epidermal thickness and decreased papillary dermal thickness. Increased elastin content with topical 20% glycolic acid and 0·05% tretinoin. No control group	Hyperpigmentation	Comparative study	4
Adatto and Deprez⁹¹	Sand abrasion and 15% TCA then post-peel cream	Therapeutic	All types	1–8 treatments (mean 4·2)	69	Average improvement of 70% on all types of striae and locations. Results better in striae rubrae.	PIH at 4 weeks especially in darker skin	Case series	4
Deprez⁹²	TCA then post-peel cream	Therapeutic	Not stated	50% TCA, up to eight treatments	50	Striae reduced in depth. Almost all patients had 60–75% improvement at end of treatment No control and no randomization in this study	Erythema and hyperpigmentation	Case series	4
Mazzarello et al.⁹³	Group A (striae rubrae) = 70% glycolic acid vs. placebo. Group B (striae albae) = 70% glycolic acid vs. placebo	Therapeutic	All types	Six treatments over 6 months	40	Decrease in furrow width of striae in both groups. Striae rubrae showed decrease in haemoglobin and striae albae an increase in melanin. Patient's other thigh acted as control	None stated	Nonrandomized controlled trial	3
Total studies: 16	LOE-1: 0; LOE-2: 10; LOE-3: 3; LOE-4: 3

C, control; PIH, postinflammatory hyperpigmentation; RCT, randomized controlled trial; T, treatment; TCA, trichloroacetic acid.

Table 8. Summary and levels of evidence for laser, light and miscellaneous therapies used to treat striae distensae (SD). ¹²⁹
Author	Device evaluated	Striae type	Fitzpatrick skin type	Wavelength and regimen	No. of subjects (T/C)	Outcome	Adverse effects	Study design	Level of evidence
McDaniel et al.¹⁰⁶	PDL	Albae 38, rubrae 1	Not stated	585-nm. Four protocols (spot diameter, fluence): 1 = 10 mm, 2·5 J cm⁻²; 2 = 10 mm, 3·0 J cm⁻²; 3 = 7 mm, 2·0 J cm⁻²; 4 = 7 mm, 4·0 J cm⁻²	39	The 10-mm spot size with 3·0 J cm⁻² improved the SD better than other treatment protocols. Significant reduction in skin shadowing in SD with all protocols (shadow profilometry). Normal-appearing elastin in SD treated with low-fluence PDL	Mild transient purpura or slight erythema	Nonrandomized controlled trial	3
Jimenez et al.¹¹³	PDL	Albae 11, rubrae 9	II–IV	585-nm, two treatments at baseline and at week 6	20	No significant difference between control and treated SD after 12 weeks.13/20 and 9/20 subjects had decreased area of striae in treated and nontreated areas, respectively. None of the striae albae had a change in colour. Four of nine striae rubrae showed improvement	PIH in one patient	Nonrandomized controlled trial	3
Nehal et al.¹¹⁴	PDL	Albae	Not stated	585-nm, 10 mm spot size and fluence of 4·25 J cm⁻². Treated at 2-month intervals for 1–2 years	5	Subjectively reported slightly improved appearance of SD. No pre- or post-treatment photographic improvement. Histologically no significant changes reported following treatment	PIH in darker skin types	Case series	4
Suh et al.¹⁰⁵	PDL/RF	Albae 36, rubrae 1	III–IV	585-nm, three treatments at baseline, Thermage RF device used with fluences 53–97 J cm⁻² (dial setting 10·5–13·5) with 2–3 passes. (PDL/RF), week 4 (PDL), week 8 (PDL)	37	Subjective assessment showed 89% of patients had 'good and very good' overall improvement in SD while 59% in were graded 'good and very good' in elasticity. No control and no randomization in this study	Transient purpura (16%) and PIH (3%)	Case series	4
Goldman et al.³⁶	Nd:YAG laser	Rubrae	II–IV	1064-nm, average number of treatment sessions was 3·45 with an interval of 3–6 weeks	20	Results considered as excellent by 55% and 40% of patients and doctors, respectively. No control and no randomization in this study	Minimal oedema and erythema	Case series	4
Tay et al.¹⁰⁷	Nonablative diode laser	Albae 9, rubrae 2	IV–VI	1450-nm, three treatments at 6-week intervals	11	No patients showed any noticeable improvement compared with control areas (one side of the body was treated with other side acting as control). Not all outcomes are reported in the results	Transient erythema, PIH (64%, n = 7)	RCT	2
de Angelis et al.³²	Er:glass fractional nonablative laser	All types	II–IV	1540-nm, 2–3 passes, 2–4 total treatments at 6-week intervals	51	50% or greater overall improvement at 6 months (unblinded assessment), 51–75% improvement (blinded assessment). No control in this study	Transient oedema, erythema, PIH	Case series	4
Stotland et al.¹¹⁵	Er:glass fractional nonablative laser	Albae 13, rubrae 1	I–IV	1550-nm, 8–12 passes with fluences of 12–18 J cm⁻², six treatments in total	14	Overall improvement of 26–50% in 63% of patients (n = 5), < 25% improvement in dyschromia in 50% of patients (n = 4), improved texture of 26–50% in 50% of patients (n = 4). Untreated striae acted as controls.	Post-treatment oedema, erythema and papules	RCT	2
Guimarães et al.¹¹⁶	Er:glass fractional nonablative laser	Rubrae	Not stated	1540-nm, eight sessions in total	10	Post-breast augmentation SD. Three patients completed eight treatments. One month after the last treatment, all patients showed a marked improvement in the striae. No controls or randomization	Post-laser erythema, PIH in 10% (n = 1)	Case series	4
Yang and Lee¹¹⁷	Er:glass fractional nonablative laser vs. ablative fractional CO₂ laser	Albae	IV	Er:glass 1550-nm at a pulse of 50 mJ and spot density 100 spots cm⁻². CO₂ pulse energy 40–50 mJ and spot density 75–100 spots cm⁻². Three treatments at 4-week intervals	22	Abdomen split into two halves and each half randomized to one of the two treatments. No statistical difference between the two lasers but significant clinical and histological improvement comparing pre- and post-treatment. No control used	PIH (36%)	Comparative study	4
Goldberg et al.¹¹⁰	XeCl excimer UVB laser vs. UVB light device	Albae	II–IV	Up to 10 treatments, XeCl 308-nm, UVB 290–320-nm	10	Increased melanin, hypertrophy and increased number of melanocytes in all treated SD. Maintained at 6 months. No control and no randomization in this study	Not stated	Comparative study	4
Goldberg et al.¹¹⁸	XeCl excimer laser	Albae	II–IV	308-nm, treatments continued until 15 completed or > 75% increase in pigmentation	75	Clinically evident improvement in striae reported in 80% of subjects. Average of 8·4 treatments. For the first 10 patients, half the area of trunk/extremity acted as a control. In the remaining 65, both sides were treated	Erythema (100%)	Case series	4
Ostovari et al.¹¹⁹	XeCl excimer laser	Albae	I–IV	308-nm, weekly until 10 treatments completed or until 100% repigmentation	10	80% of patients had a poor or moderate result based on photographs and 70% based on patients' self-assessment.	PIH	Nonrandomized controlled trial	3
Alexiades-Armenakas et al.¹²⁰	XeCl excimer laser	Albae	Not stated	308-nm, every 2 weeks until maximum of 10 treatments, 75% or 100% increase in colorimetric or visual pigment correction, respectively	9	68% improvement in mean pigmentation relative to normal skin control. Mean percentage pigmentation 102% compared with control. Overall excellent pigment correction maintained to 2 months follow-up	Transient erythema	RCT	2
Longo et al.¹⁰⁴	Copper bromide laser	Not stated	II–III	577-nm, 1–5 sessions 1 month apart	15	Five out of 15 subjects experienced complete disappearance of striae, other subjects: 50–90% improvement of dimensions. In 13/15 results were maintained after 1 year. No control and no randomization in this study	Erythema	Case Series	4
Al-Dhalimi and Abo Nasyria¹²¹	IPL 650-nm vs. 590-nm	Rubrae	III–IV	Two cut-off filters used 590-nm on left and 650-nm on right, starting fluence 13 J cm⁻² increased to 15·5 J cm⁻². Five sessions at 2-week intervals	20	Significant reduction in total number of SD on right from 256 to 240. Significant reduction in SD on left from 251 to 228. Also decreased sum of lengths and maximum widths. No control and no randomization in this study	Severe erythema (60%, n = 6)	Comparative study	4
Hernández-Pérez et al.¹⁰⁰	IPL	Albae	80% IV, 20% III	515–1200-nm, five sessions once every 2 weeks	15	Sum of the total length of striae reduced from 375to 239 cm. Reduced number of striae from a total of 117 to 94. Significant difference in post-treatment dermal thickness. No control and no randomization in this study	PIH (40%)	Case Series	4
Sadick et al.¹⁰⁸	UVA/UVB light therapy (Multiclear^TM)	Albae	II–IV	UVB 296–315-nm, UVA1 360–370-nm, twice weekly for maximum of 10 treatments	9	Five subjects had completely repigmented striae, three had 76–100% improvement and one had 51–75% improvement. Improvement only short term. No randomization in this study	PIH (> 50%)	Nonrandomized controlled trial	3
Trelles et al.¹⁰⁹	Infrared light system (NovaPlus)	Albae	II–IV	Three passes per session over four sessions, 15 days apart	10	Four patients reported results as 'fair', two as 'better' and four as 'same'. 3D optical skin imaging showed improvement of 25–50% in depth corresponding to SD. Histology showed improvements compared with specimens at baseline. No control and no randomization in this study	Minimal erythema for 24 h	Case series	4
Manuskiatti et al.¹¹¹	RF device	Albae 16, rubrae 1	IV–V	Six, weekly treatments. TriPollar RF device (3 electrodes) used at range of 40–50 W and frequency range 1 MHz	17	38% and 12% of subjects had 25–50% and 51–75% improvement in striae, respectively, on assessment. 12%, 23% and 65% of subjects rated their contentment as slightly satisfied, satisfied and very satisfied, respectively. No control and no randomization in this study	None reported	Case series	4
Suh et al.¹²²	Plasma fractional RF and platelet-rich plasma and ultrasound	Not stated	III–V	Fortnightly for total of four sessions	18	Two blinded reviewers rated 'excellent' results (75–100% improvement) in 33% (n = 6) of subjects, 'very good' (50–74% improvement) in 38·9% (n = 7), 'good' (25–49% improvement) in 22·4% (n = 4) and 'mild' (1–24% improvement) in 5·6% (n = 1). No control and no randomization in this study	PIH (11%)	Case series	4
Kim et al.¹²³	Intradermal RF and autologous platelet-rich plasma	Not stated	IV	Three sessions once every 4 weeks, RF device frequency of 1134 kHz	19	Objective assessment demonstrated 5% of patients with excellent improvement (n = 1), 37% with marked improvement (n = 7), 32% with moderate improvement (n = 6) and 26% with mild improvement (n = 5). No control and no randomization in this study	Transient bruising lasting 3–7 days (100%)	Case series	4
Ryu et al.¹²⁴	Fractionated microneedle RF vs. fractional CO₂ laser	Not stated	IV	Three treatment groups: fractional CO₂ laser (n = 10), microneedle RF (n = 10), and both (n = 10)	30	Improvement evaluated on a visual analogue scale 1–4 (1 = minimal improvement or steady state, 4 = near total improvement), was 2·2 in the fractional CO₂ laser-treated group, 1·8 in the microneedle RF-treated group and 3·4 in the combination group. A thickened epidermis and increase in collagen fibres observed in the combination-treated sites. No control and no randomization in this study	Transient PIH, pain and pruritus	Comparative study	4
Lee et al.⁷⁹	Short-pulsed CO₂ laser	Albae	IV	10 600-nm	27	Results showed that 7% (n = 2) had > 75% improvement, 52% (n = 14) had 51–75% improvement, 33% (n = 9) had 26–50% improvement and 7% (n = 2) had 0–25% improvement. No control and no randomization in this study	Short-term erythema (100%) 4 weeks and mild PIH resolving within 4 weeks	Case series	4
Nouri et al.¹²⁵	Short-pulsed CO₂ laser vs. control vs. PDL	Not stated	IV–VI	CO₂ 10 600-nm, two passes then saline wash. PDL 585-nm	4	At 20-week follow-up, type IV skin showed no improvement with PDL, type VI showed hyperpigmentation. The short pulsed CO₂ showed persistent erythema and marked hyperpigmentation in types IV and VI skin respectively	Persistent erythema and PIH in skin types IV and VI with CO₂ laser	Nonrandomized controlled trial	3
Bak et al.¹¹²	Fractional photothermolysis (Fraxel SR 1500)	Rubrae 16, albae 6	Not stated	1500-nm, two sessions of eight passes at 4-week intervals	22	27% (n = 6) of patients showed marked improvement of SD while 63% (n = 16) showed mild improvement. Significant increase in average epidermal and dermal thickness from baseline. No control and no randomization in this study	Erythema, mild pigmentation, PIH (9%)	Case series	4
Abdel-Latif and Albendary¹⁰³	Microdermabrasion	Rubrae 12, albae 8	II–IV	Five treatments at weekly intervals	20	Other half of body acted as control. 'Good to excellent' improvement in striae in 50% of subjects. Remaining 50% had 'mild to moderate' improvement. Most improvement in striae rubrae. Significantly increased type I procollagen α1 mRNA in treatment compared with controls. No randomization	Transient erythema (25%, n = 5) and PIH (20%, n = 4)	Nonrandomized controlled trial	3
Shin et al.¹²⁶	Group A (3 areas) = laser/laser and collagen/collagen. Group B (3 areas) = laser/laser and placebo/placebo	Albae	III–IV	Succinylated atelocollagen and ablative fractional resurfacing laser, three laser treatments at 4-week intervals	12	Clinical improvement scores evaluated by two doctors found a significant difference between atelocollagen and placebo sites after laser treatment and also between atelocollagen and placebo. No randomization	Erythema (100%) for 2–3 days, PIH (75%), one patient developed psoriasis	Nonrandomized controlled trial	3
Aust et al.¹²⁷	Percutaneous collagen induction therapy	Not stated	Not stated	Single 30-min procedure	22	At 6 months follow-up improved skin texture, skin tightening, dermal neovascularization and no change in pigmentation. Increased collagen I and elastin on biopsy. No control and no randomization in this study	None reported	Case series	4
Park et al.¹²⁸	Needling therapy	Albae 11, rubrae 5	III–IV	Three treatments at 4-week intervals	16	Results reported were that 37% (n = 6) of patients were highly satisfied, 50% (n = 8) were somewhat satisfied and 13% (n = 2) were unsatisfied. Increased collagen was found in the dermis post-treatment and the fragmented dermal elastin fibres normalized post-treatment. No control and no randomization in this study	Pain, erythema, spotty bleeding and pruritus	Case series	4
Total studies: 30	LOE-1: 0; LOE-2: 3; LOE-3: 7; LOE-4: 20

Er, erbium; IPL, intense pulsed light; Nd:YAG, neodymium-doped YAG; PDL, pulsed-dye laser; PIH, postinflammatory hyperpigmentation; RCT, randomized controlled trial; RF, radiofrequency; UV, ultraviolet.