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Familial risk estimation in systemic sclerosis
Author(s) -
Englert H.,
SmallMcMahon J.,
Chambers P.,
O'Connor H.,
Davis K.,
Manolios N.,
White R.,
Dracos G.,
Brooks P.
Publication year - 1999
Publication title -
australian and new zealand journal of medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.596
H-Index - 70
eISSN - 1445-5994
pISSN - 0004-8291
DOI - 10.1111/j.1445-5994.1999.tb01586.x
Subject(s) - medicine , first degree relatives , concordance , population , disease , epidemiology , systemic disease , multiple sclerosis , family aggregation , cohort , risk factor , relative risk , pediatrics , demography , family history , immunology , environmental health , confidence interval , sociology
Background : Familial systemic sclerosis has been rarely reported. Assumptions have therefore been made implying no familial disease aggregation. This study critically challenges the assumption using a methodical population‐based epidemiological approach to quantify the prevalence and characteristics of familial systemic sclerosis. Methods : In this retrospective cohort study the systemic sclerosis prevalence in first degree family members was compared between 715 systemic sclerosis patients (710 families) and 371 randomly ascertained age and gender group‐matched general practice controls (371 families). These data, obtained by telephone questionnaire (living patients) or medical records review (deceased patients and untraceable patients of unknown living status), were validated, where necessary, and expressed in terms of relative risk, absolute risk and population point prevalence. Results : Systemic sclerosis affecting first degree members was validated in ten of 710 families. Reporting of systemic disease in another four more distant family members, and the co‐occurrence of systemic and localised disease in three families was also documented. Observed and expected disease subtype concordance was 80% (44–97%) and 68% respectively and the female predominance among familial cases was similar to that for non‐familial disease. The risk of disease in a subsequent first degree relative was compared to the risk in an initial first degree family member. Its estimated magnitude was wide (11–158). However, use of population prevalence data to determine the expected number of systemic sclerosis patients in the negative cohorts' families suggests the higher estimate is more realistic. Despite the high magnitude, the absolute disease risk in first degree family members remained low – approximating 1%. The population prevalence of familial systemic sclerosis approximated 1.4/million. Conclusions : This study substantially increases the otherwise small list of documented instances of familial systemic sclerosis. More importantly, it quantifies the risk for the first time, ranking it as the disease's most powerful determinant identified to date.