Table 4.

RCTs comparing topical tretinoin versus vehicle.

Ref	Number of people	Treatment, dose, duration	Results	Comment
	256 people with mild to moderate acne	Tretinoin 0.05% v tretinoin 0.02% v vehicle twice daily, for 8 weeks	Total lesion count: No data reportedNon-inflammatory lesions: Tretinoin at either dose significantly reduced comedones at 7–8 weeks compared with vehicle (measured by total score: 89 with 0.05%, 94 with 0.02% v 131 with vehicle; P less than 0.01 for either dose v vehicle)Inflammatory lesions: Tretinoin 0.05% significantly reduced papules at 7–8 weeks compared with vehicle, no significant difference between tretinoin 0.02% and vehicle (61 with 0.05% tretinoin, 76 with 0.02% tretinoin v 83 with vehicle; P less than 0.05 for 0.05% tretinoin v vehicle; P = NS for 0.02% tretinoin, CI not reported)Patient perception of improvement: No data reportedAdverse effects: Significantly increased erythema, peeling, or both at 1–3 weeks compared with vehicle (86% with tretinoin 0.05% v 81% with tretinoin 0.02% v 40% with vehicle; P less than 0.01 for either dose v vehicle)	Completer analysis only, no intention-to-treat analysis
	257 people with moderate to severe acne	Tretinoin 0.05% v motretinide 0.1% v vehicle twice daily, for 8 weeks	Total lesion count: No data reportedNon-inflammatory lesions: Tretinoin significantly reduced non-inflammatory lesions at 8 weeks (number of lesions: 89 with tretinoin v 131 with vehicle; P = 0.01) Inflammatory lesions: Tretinoin significantly reduced papules at 8 weeks (number of papules: 61 with tretinoin v 83 with vehicle; P = 0.05) Patient perception of improvement: No data reportedAdverse effects: Tretinoin significantly increased proportion of people who had erythema and desquamation (76/84 [90%] with tretinoin v 16/84 [19%] with vehicle); burning (69/84 [82%] v 23/84 [27%]); and pruritis (62/84 [74%] v 26/84 [31%]) over 8 weeks. P less than 0.005 for all outcomes
	60 people with mild to moderate acne	Tretinoin 0.05% v tretinoin 0.025% v vehicle, for 12 weeks	Total lesion count: No data reportedNon-inflammatory lesions: No data reported Inflammatory lesions: No data reportedPatient perception of improvement: Patient perception of severity on a visual analogue scale (18 with tretinoin v 39 with vehicle; range of scale not specified) Adverse effects: People taking tretinoin 0.05% or 0.025% had erythema, soreness, and irritation	No results comparing groups directly reported; no assessment of significance in changes in outcomes from baseline within group
	215 people with mild to moderate acne	Tretinoin 0.025% v tretinoin 0.025% plus polyolprepolymer-2 v vehicle once daily, for 12 weeks	Total lesion count: Tretinoin 0.025% significantly reduced total lesion count compared with vehicle (% reduction: 40% with tretinoin v 24% with vehicle; P less than 0.05) Non-inflammatory lesions: Tretinoin 0.025% alone significantly reduced non-inflammatory lesions at 12 weeks compared with vehicle (% reduction: 39% with tretinoin v 19% with vehicle; P less than 0.05) Inflammatory lesions: Tretinoin 0.025% alone significantly reduced papules at 12 weeks compared with vehicle (% reduction: 42% with tretinoin v 19% with vehicle; P less than 0.05)Patient perception of improvement: No data reportedAdverse effects: Tretinoin 0.025% alone significantly increased proportion of people who had erythema (20% with tretinoin v 9% with vehicle); peeling (21% v 3%); and dryness (21% v 8%). P less than 0.005 for all outcomes	Absolute results estimated from graph
	271 people with mild to moderate acne	Tretinoin 0.025% v tretinoin 0.025% plus polyolprepolymer-2 v vehicle once daily, for 12 weeks	Total lesion count: Tretinoin 0.025% significantly reduced total lesion count compared with vehicle (% reduction: 39% with tretinoin v 28% with vehicle; P less than 0.05) Non-inflammatory lesions: Tretinoin 0.025% alone significantly reduced non-inflammatory lesions at 12 weeks compared with vehicle (% reduction: 49% with tretinoin v 31% with vehicle; P less than 0.05). Inflammatory lesions: Tretinoin 0.025% alone significantly reduced papules at 12 weeks compared with vehicle (% reduction: 49% with tretinoin v 28% with vehicle; P less than 0.05)Patient perception of improvement: No data reportedAdverse effects: Tretinoin 0.025% alone significantly increased proportion of people who had erythema: 8% with tretinoin v 3% with vehicle; burning: 8% v 3%; itching: 15% v 6%; and tightness: 22% v 15%. P less than 0.005 for all outcomes	Absolute results estimated from graph

Ref, reference.