Table 2. Association of AK With cSCC in Relation to Demographic Characteristics in 220 236 Patients With AK and 220 236 Matched Control Patients.
| Characteristic | Prevalence, % | Patients with AK/control patients | Subdistribution HR (95% CI)a | |
|---|---|---|---|---|
| Follow-up, median (IQR), y | No. with cSCC | |||
| AK | 50.0 | 4.2 (1.9-7.1) | 19 620 | 1.90 (1.85-1.95) |
| Controlb | 50.0 | 3.2 (1.2-6.1) | 7095 | 1 [Reference] |
| Period of initial AK visit | ||||
| 2009-2010 | 21.5 | 9.2 (4.4-10.1)/4.8 (1.2-9.6) | 7213/2613 | 1 [Reference] |
| 2011-2012 | 19.5 | 7.4 (4.2-8.2)/7.0 (2.0-8.0) | 5411/1955 | 0.95 (0.92-0.98) |
| 2013-2015 | 26.2 | 5.0 (4.2-6.0)/4.8 (2.8-5.8) | 4727/1729 | 0.82 (0.79-0.85) |
| 2016-2017 | 16.1 | 2.9 (2.4-3.5)/2.8 (2.3-3.4) | 1654/562 | 0.76 (0.72-0.79) |
| 2018-2019 | 16.7 | 1.0 (0.5-1.5)/1.0 (0.5-1.5) | 615/236 | 0.67 (0.63-0.72) |
| Age group, y | ||||
| 18-49 | 12.1 | 4.2 (1.7-7.3)/3.8 (1.6-7.0) | 790/101 | 1 [Reference] |
| 50-59 | 24.6 | 4.6 (2.1-7.5)/3.8 (1.5-6.8) | 3056/768 | 1.97 (1.84-2.12) |
| 60-69 | 33.7 | 4.3 (1.9-7.3)/3.0 (1.1-6.0) | 6398/2421 | 3.54 (3.30-3.79) |
| 70-79 | 18.9 | 4.1 (1.8-6.9)/2.9 (1.1-5.8) | 5518/2280 | 5.78 (5.39-6.20) |
| ≥80 | 10.7 | 3.4 (1.6-5.9)/2.2 (0.8-4.5) | 3858/1525 | 8.18 (7.62-8.78) |
| Sex | ||||
| Female | 52.5 | 4.3 (1.9-7.2)/3.4 (1.4-6.4) | 9469/3306 | 1 [Reference] |
| Male | 47.5 | 4.1 (1.8-7.0)/2.9 (1.1-5.8) | 10 151/3789 | 1.40 (1.37-1.43) |
| Race/ethnicity | ||||
| African American | 0.2 | 4.3 (2.3-7.0)/4.2 (1.9-6.9) | 8/0 | 0.15 (0.07-0.29) |
| Asian American | 1.4 | 4.0 (1.8-6.7)/3.8 (1.7-6.6) | 66/10 | 0.19 (0.15-0.24) |
| Hispanic | 4.1 | 4.0 (1.7-6.9)/3.8 (1.6-6.8) | 535/58 | 0.45 (0.42-0.49) |
| White | 89.5 | 4.2 (1.9-7.2) /3.1 (1.2-6.0) | 18 106/6873 | 1 [Reference] |
| Other or multiple | 4.8 | 4.2 (1.9-7.0)/3.6 (1.5-6.7) | 905/154 | 0.69 (0.65-0.73) |
| History of BCC | ||||
| Yes | 12.8 | 4.1 (1.8-6.9)/2.3 (0.8-4.9) | 6396/1279 | 1.83 (1.78-1.89) |
| No | 87.2 | 4.3 (1.9-7.2)/3.3 (1.3-6.2) | 13 224/5816 | 1 [Reference] |
Abbreviations: AK, actinic keratosis; BCC, basal cell carcinoma; cSCC, cutaneous squamous cell carcinoma; HR, hazard ratio; IQR, interquartile range.
a
The Cox proportional hazards regression model includes year of AK visit, age, sex, race/ethnicity, and history of BCC as coded in the table.
b
General population control patients were matched to patients with AK on year, age, sex, race/ethnicity, and medical center, and they were assigned an index date corresponding to the initial visit date plus 30 days for the patients with AK.