Table 1

Comparison of the development of spinal DJD among patients taking different dosages of statins, age, gender, comorbidities and monthly income

Statin dosage	No. of DJD events	Person-years	Incident rate†	Adjusted HR (95% CI)	P value
Statin non-users	13 572	1 084 974	1.25	0.66 (0.58 to 0.74)	<0.001*
≤Q1‡	290	11 289	2.57	1.00
Q1–Q2‡	276	11 518	2.40	0.93 (0.79 to 1.10)	0.382
Q2–Q3‡	255	11 643	2.19	0.83 (0.70 to 0.99)	0.035*
>Q3‡	240	11 166	2.15	0.81 (0.68 to 0.97)	0.019*
Age (years)
40–49	6374	666 085	0.96	1.00
50–59	5503	338 763	1.62	1.59 (1.53 to 1.65)	<0.001*
60–65	2756	125 741	2.19	1.99 (1.89 to 2.08)	<0.001*
Gender
Female	8670	548 130	1.58	1.00
Male	5963	582 460	1.02	0.66 (0.64 to 0.68)	<0.001*
Comorbidity
Diabetes mellitus	1128	55 434	2.03	0.79 (0.74 to 0.85)	<0.001*
Hyperlipidaemia	1070	47 835	2.24	1.14 (1.07 to 1.22)	<0.001*
Cardiovascular disease	3632	165 865	2.19	1.31 (1.26 to 1.37)	<0.001*
Chronic kidney disease	74	3518	2.10	0.80 (0.63 to 1.01)	0.061
CCI
0	9103	861 293	1.06	1.00
1	3303	178 008	1.86	1.54 (1.47 to 1.60)	<0.001*
2	1352	58 422	2.31	1.83 (1.72 to 1.94)	<0.001*
≥3	875	32 866	2.66	2.03 (1.88 to 2.20)	<0.001*
Monthly income (US$)
≤600	7320	543 565	1.35	1.00
600–1400	2140	430 205	0.50	0.99 (0.94 to 1.05)	0.707
>1400	3676	156 820	2.34	0.89 (0.85 to 0.94)	<0.001*

*P<0.05.
†Per 100 person-years.
‡Q1, statin dosage of 5400 mg; Q2, statin dosage of 11 900 mg; Q3, statin dosage of 28 000 mg.
CCI, Charlson Comorbidity Index; DJD, degenerative joint disease.