Table 3.

Incidence of anal squamous cell carcinoma in people living with HIV in Australia, 1982–2012, by time period, attained age, HIV exposure route, and CD4⁺ cell count at HIV diagnosis, and history of an AIDS-defining diagnosis.

	Person years	Cases	Incidence (per 100 000)	IRR	95% CI	P value	Adjusted IRR^a	95% CI	P value
Time period						<0.001			<0.001
1982–1995	74 236.6	11	14.82	1	–		1	–
1996–1999	48 109.0	9	18.71	1.26	0.52–3.05		1.41	0.58–3.47
2000–2004	73 425.6	24	32.69	2.21	1.08–4.50		2.63	1.23–5.58
2005–2008	72 622.7	31	42.69	2.88	1.45–5.73		3.62	1.65–7.92
2009–2012	87 012.7	54	62.06	4.19	2.19–8.01		5.53	2.65–11.52
Attained age (years)						<0.001			0.229
16–44	19 6858.4	44	22.35	1	–		1	–
45–59	122556.6	62	50.59	2.26	1.54–3.33		1.37	0.88–2.12
≥60	35 970.8	23	63.94	2.86	1.73–4.74		1.37	0.75–2.52
HIV exposure route						0.003			0.002
Other routes	88 343.5	17	19.24	1	–		1	–
Male homosexual	26 7063.2	112	41.94	2.18	1.31–3.63		2.25	1.35–3.76
CD4⁺ cell count at HIV diagnosis						0.003^b			0.569^b
<50	14 121.5	7	49.57	1	–		1	–
50–199	20 644.2	13	62.97	1.27	0.51–3.18		1.49	0.59–3.75
200–499	46 933.3	14	29.83	0.60	0.24–1.49		0.92	0.36–2.40
≥500	49 200.5	9	18.29	0.37	0.14–0.99		0.58	0.20–1.68
Missing	22 4507.1	86	38.31	0.77	0.36–1.67		1.16	0.53–2.51
History of AIDS						<0.001			<0.001
No	20 0604.3	49	24.43	1	–		1	–
Yes	15 4802.3	80	51.68	2.12	1.48–3.02		2.25	1.45–3.48

CI, confidence interval; IRR, incidence rate ratio.

Adjusted for time period, attained age, HIV exposure route, CD4⁺ cell count at time of HIV diagnosis, a history of AIDS.

Excluding those who had missing CD4⁺ at time of HIV diagnosis.