Epidemiology of Systemic Sclerosis in a Large US Managed Care Population

Article Figures & Data

Table 1.

Characteristics of subjects with systemic sclerosis (SSc) (2003–2008).

Characteristic	Incidence Cohort Subjects n (%)	Prevalence Cohort Subjects n (%)
SSc (overall)	1529 (100.0)	2739 (100.0)
Year
2003	226 (14.8)	656 (24.0)
2004	220 (14.4)	725 (26.5)
2005	232 (15.2)	757 (27.6)
2006	304 (19.9)	918 (33.5)
2007	278 (18.2)	966 (35.2)
2008	269 (17.6)	1076 (39.3)
Age, yrs
18–44	430 (28.1)	732 (26.7)
45–64	916 (59.9)	1682 (61.4)
65+	183 (12.0)	325 (11.9)
Sex
Female	1297 (84.8)	2357 (86.1)
Male	232 (15.2)	382 (14.0)
Medications (1 Year postindex)
Methotrexate	152 (9.9)	246 (9.0)
Cyclosporine	10 (0.7)	13 (0.5)
Cyclophosphamide	39 (2.6)	75 (2.7)
Mycophenolate mofetil	67 (4.4)	132 (4.8)
Corticosteroids	707 (46.2)	1213 (44.3)

Table 2.

Systemic Sclerosis incidence (2003–2008).

	Incidence (per 100,000)^*
	Crude Rate	Age and Sex Adjusted Rate	95% CI, Adjusted Rate
Annual incidence
2003	4.6	5.4	4.5–6.2
2004	4.2	4.8	4.0–5.6
2005	4.2	5.1	4.2–5.9
2006	5.2	6.0	5.1–6.9
2007	4.7	6.3	5.3–7.3
2008	4.6	6.0	5.0–6.9
Overall incidence (2003–2008) and sensitivity analysis
SSc base-case analysis	4.6	5.6	5.2–6.0
Presence of specialist visit on index date^**	2.2	2.5	2.3–2.8
Presence of specialist visit in the year following index date^**	3.6	4.2	3.9–4.6
Presence of select drugs 1 year following index date^†	2.3	2.8	2.5–3.0
Presence of any of the above^††	3.9	4.7	4.4–5.1

↵* Rates are per 100,000 individuals for yearly rates, and are per 100,000 person-years for overall rates.
↵** Specialist included rheumatologist, dermatologist, or nephrologist.
↵† Drugs included immunosuppressants (methotrexate or cyclosporine) and/or systemic corticosteroids (betamethasone, corticotropin, dexamethasone, methylprednisolone, prednisone, or triamcinolone).
↵†† Determined for specialist visit, immunosuppressant use, and/or corticosteroid use, using the same time frames as described above.

Table 3.

Annual SSc prevalence (2003–2008).

Year	Annual SSc Prevalence (per 100,000 individuals)	95% CI
Base-case analysis
2003	13.5	12.4–14.5
2004	13.7	12.7–14.7
2005	13.6	12.7–14.6
2006	15.6	14.6–16.6
2007	16.2	15.1–17.2
2008	18.4	17.3–19.5
Sensitivity analysis^*
2003	11.2	10.2–12.1
2004	11.5	10.6–12.4
2005	11.2	10.3–12.1
2006	13.2	12.3–14.1
2007	13.8	12.9–14.8
2008	16.0	14.9–17.0

↵* Inclusion required evidence of specialist visit (rheumatologist, dermatologist, or nephrologist) on or within a year following a prevalence date (a prevalence date was any service date that satisfied all inclusion criteria for the prevalence cohort, and specialist visit was recorded at every nonmissing prevalence date between 2003 and 2008).