Table 2.

Risk of lower respiratory tract infection according to the severity and type of brain atrophy and white matter lesions

	n	Person-years	No of events	Rate/person-years	Adjusted IRRa	95% CIa	P valuea	Fully adjusted IRRb	95% CIb	P valueb
Cortical atrophy
No/mild atrophy	27	84.2	7	0.08	1.00	Reference		1.00	Reference
Severe atrophy (any lobe)	24	70.3	18	0.26	4.15	1.14–15.06	0.031	4.60	1.18–17.93	0.028
Frontal lobe	21	61.9	16	0.26	4.46	1.12–17.73	0.034	4.75	1.23–18.35	0.024
Parietal lobe	18	54.8	16	0.29	4.90	1.16–20.77	0.031	5.23	1.32–20.74	0.018
Temporal lobe	10	28.5	5	0.18	4.20	0.48–36.40	0.193	3.28	0.69–15.62	0.136
Four cortical sulci ratio
Lower tertile	16	49.9	4	0.08	1.00	Reference		1.00	Reference
Middle tertile	17	50.7	9	0.18	4.64	0.64–33.79	0.130	3.88	0.42–35.61	0.230
Upper tertile	17	66.9	12	0.18	2.57	0.68–9.64	0.162	2.08	0.42–10.41	0.371
Ventricular dilatation
Evans ratio
Lower tertile	16	50.3	9	0.18	1.00	Reference		1.00	Reference
Middle tertile	17	44.3	12	0.27	0.71	0.30–1.64	0.420	0.61	0.19–1.93	0.398
Upper tertile	17	55.9	4	0.07	0.64	0.10–4.28	0.645	0.33	0.12–2.32	0.173
Third ventricular ratio
Lower tertile	17	49.4	12	0.24	1.00	Reference		1.00	Reference
Middle tertile	17	51.4	10	0.19	0.55	0.15–1.97	0.360	0.88	0.29–2.66	0.821
Upper tertile	16	49.7	3	0.06	0.28	0.06–1.26	0.096	0.38	0.09–1.49	0.164
White matter lesions
No/focal/confluence	24	70.1	12	0.17	1.00	Reference		1.00	Reference
Diffuse (any region)	27	84.4	13	0.15	1.07	0.30–3.84	0.919	1.40	0.39–5.05	0.608
Frontal	41	71.3	13	0.18	1.22	0.35–4.32	0.754	1.57	0.43–5.77	0.496
Parieto-occipital	38	68.8	11	0.16	1.28	0.30–5.44	0.739	1.38	0.34–5.61	0.655
Temporal	23	24.0	4	0.17	1.49	0.28–8.06	0.643	1.03	0.15–6.97	0.974

Notes:

^aAdjusted for age and sex;

^badjusted for age, sex, hypertension, mobility status by ECOG performance status (0–2 and 3–4), dementia status (oriented or not), major tranquilizer use, and lacunar infarction (non, single, and multiple). Severe brain atrophy was defined as severe atrophy in any of the frontal, temporal, parietal or occipital lobes. Four cortical sulci ratio = the sum of the widths of the four widest sulci at the two highest scanning levels/maximal transversal intracranial width. Evans ratio = maximal frontal horn width/maximal transversal intracranial width. Third ventricular ratio = maximal width of the third ventricle/maximal transversal intracranial width.

Abbreviations: IRR, incidence rate ratio; CI, confidence interval.