Table 3. Risk pattern distribution between the RA group and non-RA group for all diseases categorized in ICD-9-CM.

Disease Category	ICD-9-CM code	RA	Non-RA	RR	CI (95%)
Infectious and parasitic	001–139	2.46%	7.62%	0.32	(0.27–0.37)
Neoplasm	140–239	1.92%	0.31%	6.21	(5.71–7.28)
Endocrine, metabolic, and immunity	240–279	9.70%	0.55%	17.66	(15.36–21.74)
Blood and blood-forming organs	280–289	1.66%	0.03%	48.24	(29.23–286.57)
Psychiatric disorders	290–319	9.85%	0.14%	71.78	(51.16–144.86)
Nervous system and sense organs	320–389	20.10%	18.74%	1.07	(1.04–1.10)
Circulatory system	390–459	10.54%	0.82%	12.8	(11.55–14.79)
Respiratory system	460–519	31.45%	44.89%	0.7	(0.68–0.72)
Digestive system	520–579	35.32%	42.62%	0.83	(0.81–0.85)
Genitourinary system	580–629	16.06%	6.49%	2.48	(2.46–2.49)
Complications of pregnancy, childbirth, and puerperium	630–679	0%	0.58%	0	(0.00–0.00)
Diseases of the skin and subcutaneous tissue	680–709	8.52%	18.98%	0.45	(0.41–0.48)
Musculoskeletal system	710–739	57.18%	1.30%	43.85	(38.33–51.8)
Congenital anomalies	740–759	0%	0%	0	(0.00–0.00)
Conditions prenatal period	760–779	0%	0%	0	(0.00–0.00)
Symptoms, signs	780–799	21.91%	16.61%	1.32	(1.29–1.35)
Injury and poisoning	800–999	9.52%	17.02%	0.56	(0.52–0.60)