Rheumatoid arthritis and sleep quality

This is a transversal observational study of 112 RA patients submitted to measurement of DAS-28, Epworth scale for daily sleepiness, index of sleep quality by Pittsburg index, risk of sleep apnea by the Berlin questionnaire and degree of depression by the CES-D (Center for Epidemiologic Studies Depression scale) questionnaire. We also collected epidemiological, clinical, serological and treatment data.

Results:

Only 18.5% of RA patients had sleep of good quality. In univariate analysis a bad sleep measured by Pittsburg index was associated with daily doses of prednisone (p = 0.03), DAS-28 (p = 0.01), CES-D (p = 0.0005) and showed a tendency to be associated with Berlin sleep apnea questionnaire (p = 0.06). In multivariate analysis only depression (p = 0.008) and Berlin sleep apnea questionnaire (p = 0.004) kept this association.

Conclusions:

Most of RA patients do not have a good sleep quality. Depression and risk of sleep apnea are independently associated with sleep impairment.

Keywords:
Rheumatoid arthritis; Sleep; Sleep apnea; Depression; Pain

Studied variable	Values
Erythrocyte sedimentation rate (mm/h)	1-103 (median 35.0; IQR = 19.7-58.0)
C reactive protein (mg/dL)	0.15-80.0 (median 10.9; IQR = 5.0-20.7)
Hemoglobin	10.9-16.9 (mean 13.3 ± 1.2)
VAS global	0-100 (median 30.0; IQR = 30.0-60.0)
VAS pain	0-100 (median 60.0; IQR 30.0-80.0)
VAS fatigue	0-100 (median 50.0; IQR 0-80.0)
Body mass index (kg/m²)	17.3-46.4 (median 27.5; IQR = 24.3-31.5) • Underweight (<18.5) - 4/112 = 3.5% • Normal (18.6-24.9) - 29/112 = 25.8% • Overweight (25-29.9) - 43/112 = 38.3% • Obesity (≥30) - 36/112 = 32.1%
DAS-28 (ESR)	0.28-7.38 (mean 3.75 ± 1.28)
Epworth sleepiness scale	0-24.0 (median 6.0; IQR 3.0-12.0) • Normal = 79/112 (70.5%) • Pathological somnolence = 12/112 (10.7%) • Significant somnolence = 21/112 (18.7%)
Berlin or sleep apnea screening questionnaire	0-3.0 (median 1.0; IQR = 3.0-2.0) • Low risk of sleep apnea = 58/112 (51.7%) • High risk of sleep apnea = 54/112 (48.2%)
Pittsburg sleep quality index	1-18 (median 9.0; IQR 5.0-18.0) • Sleep of good quality = 21/112 (18.5%) • Sleep disturbance = 47/112 (41.9%) • Bad sleep = 44/112 (39.2%)
Center for Epidemiologic Studies Depression Scale (CES-D)	0-60 (median 13.0; IQR = 6.0-22.0) • Normal - 63/112 = 56.1% • Depressive - 49/112 = 43.7%

	Pittsburg index ≤ 5 n = 21	Pittsburg index > 5 n = 91	p
Gender (male/female)	5/16	13/78	0.32^a a Fisher test.
Tabagism (smokers/not smokers)	5.2%	14.2%	1.00^a a Fisher test.
Ethnic background (Afrodescendants/Caucasians)	2/18	20/71	0.35^a a Fisher test.
Mean age (years)	58.4 ± 2.2	54.7± 10.6	0.15^b b Unpaired t test.
Mean age at diagnosis (years)	45.0 ± 15.6	42.5 ± 11.56	0.42^b b Unpaired t test.
Median body mass index (kg/m²)	26.7 (IQR = 22.3-28.6)	27.6 (IQR = 24.7-31.59)	0.25^c c Mann Whitney test.
Positive rheumatoid factor	47.6%	61.5%	0.24^c c Mann Whitney test.
Positive anti-CCP	30%	50.9%	0.30^a a Fisher test.
Positive antinuclear antibody	40%	33.7%	0.59^d d Chi squared test.
Median C reactive protein (mg/L)	11.0 (IQR = 6.0-20.8)	10.7 (IQR = 5.0-20.7)	0.85^c c Mann Whitney test.
Median hemoglobin (g/dL)	13.5 (IQR = 12.0-14.0)	13.4 (IQR = 12.4-14.0)	0.80^c c Mann Whitney test.
Median prednisone dose (mg/day)	5.0 (IQR = 0.0-5.0)	5.0 (IQR = 5.0-10.0)	0.03^c c Mann Whitney test.
Metotrexate users	71.4%	73.9%	0.83^d d Chi squared test.
Leflunomide users	42.8%	43.9%	0.92^d d Chi squared test.
Antimalarial users	19.04%	21.9%	1.00^a a Fisher test.
Biologic medication users	9.5%	9.8%	1.00^a a Fisher test.
Median sedimentation rate	26.0 (IQR = 13.5-47.5)	39.0 (IQR = 21.0-60.0)	0.12^c c Mann Whitney test.

Sociedade Brasileira de Reumatologia Av Brigadeiro Luiz Antonio, 2466 - Cj 93., 01402-000 São Paulo - SP, Tel./Fax: 55 11 3289 7165 - São Paulo - SP - Brazil
E-mail: sbre@terra.com.br

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[1] *Corresponding author. E-mail: tskare@onda.com.br (T.L. Skare).