Abstract
Objective: To assess the incidence of chronic persistent rheumatoid arthritis (RA) in a population-based cohort of twins and to determine the impact of smoking. Methods: In a historical cohort study on twins born in 1920 to 1982, we identified 157 cases of RA among 45,280 responders (response rate 80%). Information on smoking was obtained by questionnaire and interview. A mixed-effects Poisson regression model was used to estimate incidence rate ratios with age, sex, smoking duration, and smoking intensity as covariates. We used the SplitLexis procedure in the Epi R package to study a possible effect of period or cohort in addition to age on the variation of the incidence. Results: The annual incidence of chronic persistent RA was 18.8 per 100,000 person-years, ages 15–73 years (females 25.2, males 12.0), increasing with age to a maximum at age 60 years in females and age 70 years in males. The incidence rate ratio among ever-smoking patients was 1.96 (95% confidence interval [95% CI] 1.43–3.76), 1.93 (95% CI 1.00–3.7) after 30 pack-years, and 1.034 (P < 0.001) per year of smoking, implying a doubling of risk after 20 years regardless of sex and smoking intensity. We did not detect significant period or cohort effects. Conclusion: The incidence of chronic persistent RA is lower than the incidence figures reported in inception cohorts. Smoking duration, but not intensity, doubled the risk of RA after 20 years of smoking in both sexes.
| Original language | English |
|---|---|
| Journal | Arthritis Care & Research |
| Volume | 69 |
| Issue number | 5 |
| Pages (from-to) | 616–624 |
| ISSN | 2151-464X |
| DOIs | |
| Publication status | Published - May 2017 |
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Keywords
- Adolescent
- Adult
- Aged
- Arthritis, Rheumatoid/epidemiology
- Cohort Studies
- Diseases in Twins/epidemiology
- Female
- Humans
- Incidence
- Male
- Middle Aged
- Risk Factors
- Smoking/adverse effects
- Time Factors
- Young Adult
Cite this
}
Incidence of chronic persistent rheumatoid arthritis and the impact of smoking : A Historical Twin Cohort Study. / Svendsen, Anders J; Junker, Peter; Houen, Gunnar; Kyvik, Kirsten O; Nielsen, Christian; Skytthe, Axel; Holst, René.
In: Arthritis Care & Research, Vol. 69, No. 5, 05.2017, p. 616–624.Research output: Contribution to journal › Journal article › Research › peer-review
TY - JOUR
T1 - Incidence of chronic persistent rheumatoid arthritis and the impact of smoking
T2 - A Historical Twin Cohort Study
AU - Svendsen, Anders J
AU - Junker, Peter
AU - Houen, Gunnar
AU - Kyvik, Kirsten O
AU - Nielsen, Christian
AU - Skytthe, Axel
AU - Holst, René
N1 - © 2016, American College of Rheumatology.
PY - 2017/5
Y1 - 2017/5
N2 - Objective: To assess the incidence of chronic persistent rheumatoid arthritis (RA) in a population-based cohort of twins and to determine the impact of smoking. Methods: In a historical cohort study on twins born in 1920 to 1982, we identified 157 cases of RA among 45,280 responders (response rate 80%). Information on smoking was obtained by questionnaire and interview. A mixed-effects Poisson regression model was used to estimate incidence rate ratios with age, sex, smoking duration, and smoking intensity as covariates. We used the SplitLexis procedure in the Epi R package to study a possible effect of period or cohort in addition to age on the variation of the incidence. Results: The annual incidence of chronic persistent RA was 18.8 per 100,000 person-years, ages 15–73 years (females 25.2, males 12.0), increasing with age to a maximum at age 60 years in females and age 70 years in males. The incidence rate ratio among ever-smoking patients was 1.96 (95% confidence interval [95% CI] 1.43–3.76), 1.93 (95% CI 1.00–3.7) after 30 pack-years, and 1.034 (P < 0.001) per year of smoking, implying a doubling of risk after 20 years regardless of sex and smoking intensity. We did not detect significant period or cohort effects. Conclusion: The incidence of chronic persistent RA is lower than the incidence figures reported in inception cohorts. Smoking duration, but not intensity, doubled the risk of RA after 20 years of smoking in both sexes.
AB - Objective: To assess the incidence of chronic persistent rheumatoid arthritis (RA) in a population-based cohort of twins and to determine the impact of smoking. Methods: In a historical cohort study on twins born in 1920 to 1982, we identified 157 cases of RA among 45,280 responders (response rate 80%). Information on smoking was obtained by questionnaire and interview. A mixed-effects Poisson regression model was used to estimate incidence rate ratios with age, sex, smoking duration, and smoking intensity as covariates. We used the SplitLexis procedure in the Epi R package to study a possible effect of period or cohort in addition to age on the variation of the incidence. Results: The annual incidence of chronic persistent RA was 18.8 per 100,000 person-years, ages 15–73 years (females 25.2, males 12.0), increasing with age to a maximum at age 60 years in females and age 70 years in males. The incidence rate ratio among ever-smoking patients was 1.96 (95% confidence interval [95% CI] 1.43–3.76), 1.93 (95% CI 1.00–3.7) after 30 pack-years, and 1.034 (P < 0.001) per year of smoking, implying a doubling of risk after 20 years regardless of sex and smoking intensity. We did not detect significant period or cohort effects. Conclusion: The incidence of chronic persistent RA is lower than the incidence figures reported in inception cohorts. Smoking duration, but not intensity, doubled the risk of RA after 20 years of smoking in both sexes.
KW - Cohort studies
KW - Incidence
KW - Rheumatoid arthritis
KW - Smoking
KW - Twins
KW - Adolescent
KW - Adult
KW - Aged
KW - Arthritis, Rheumatoid/epidemiology
KW - Cohort Studies
KW - Diseases in Twins/epidemiology
KW - Female
KW - Humans
KW - Incidence
KW - Male
KW - Middle Aged
KW - Risk Factors
KW - Smoking/adverse effects
KW - Time Factors
KW - Young Adult
U2 - 10.1002/acr.22987
DO - 10.1002/acr.22987
M3 - Journal article
C2 - 27390149
VL - 69
SP - 616
EP - 624
JO - Arthritis Care & Research
JF - Arthritis Care & Research
SN - 2151-464X
IS - 5
ER -