Table.

GRADE Evaluation of interventions for Squamous cell carcinoma of the skin (non-metastatic).

Important outcomes	Incidence rates
Studies (Participants)	Outcome	Comparison	Type of evidence	Quality	Consistency	Directness	Effect size	GRADE	Comment
Does the use of sunscreen help prevent cutaneous squamous cell carcinoma and actinic (solar) keratosis?
1 (1621)	Incidence rates	Regular sunscreen use versus discretionary or no use	4	0	0	–1	0	Moderate	Directness point deducted for restricted population (subtropical)
1 (588)	Incidence rates	Daily sunscreen use versus placebo	4	0	0	–1	0	Moderate	Directness point deducted for restricted population (all participants had previous actinic [solar] keratoses)
1 (1621)	Incidence rates	Regular sunscreen use versus discretionary or no use	4	0	0	–1	0	Moderate	Directness point deducted for restricted population (subtropical, half of participants had previous actinic [solar] keratoses)

We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.