ﻣﻮﺍﺭﺩ ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﺍپﻴﺪﻣﻴﻮﻟﻮژﻲ ﺗﻮﺻﻴﻔﻲ: ﺍﻟﻒ( ﺗﻌﻴﻴﻦ ﺑﺎﺭ ﺑﻴﻤﺎﺭﻳﻬﺎ ﻣﺜﻞ ﻣﻴﺰﺍﻥ ﺍﺑﺘﻼ ﻭ ﻣﺮگ ﻭﻣﻴﺮ ﺏ( ﺗﻮﻟیﺪ ﻓﺮﺿیﻪ ﺑﺮﺍﻱ ﺷﻨﺎﺧﺖ ﻋﻠﻞ ﺑﻴﻤﺎﺭﻳﻬﺎ )ﻛﻪ ﺑﺎ ﻣﻄﺎﻟﻌﺎﺕ ﺗﺤﻠﻴﻠﻲ ﺍﺩﺍﻣﻪ ﻣﻲﻳﺎﺑﺪ ﺗﺎ ﻋﻠﻞ ﺑیﻤﺎﺭی ﻣﻌﻠﻮﻡ ﺷﻮﺩ. ( ﺝ( ﻓﺮﺍﻫﻢ کﺮﺩﻥ ﺍﻃﻼﻋﺎﺕ ﻻﺯﻡ ﺑﺮﺍﻱ ﺑﺮﻧﺎﻣﻪﺭﻳﺰﻱ ﻭ ﺳﺎﺯﻣﺎﻧﺪﻫﻲ ﻭ ﺍﺭﺯﻳﺎﺑﻲ ﺧﺪﻣﺎﺕ ﺑﻬﺪﺍﺷﺘﻲ ﻭ ﺩﺭﻣﺎﻧﻲ ﺩ( گﺎﻡ ﺍﻭﻝ ﺑﺮﻧﺎﻣﻪﻫﺎﻱ پژﻮﻫﺸﻲ Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﺍﻧﻮﺍﻉ ﻣﻄﺎﻟﻌﺎﺕ ﺗﻮﺻیﻔی Case Report ( • گﺰﺍﺭﺵ ﻣﻮﺭﺩ )ﺑیﻤﺎﺭ Case Series • ﻣﺠﻤﻮﻋﻪ ﻣﻮﺭﺩ Cross-sectional Ecological Dr Seyyed Alireza Moravveji MD Community Medicine specialist • ﻣﻘﻄﻌﻲ • ﺍﻛﻮﻟﻮژﻴﻚ
گﺰﺍﺭﺵ ﻣﻮﺭﺩ )ﺑﻴﻤﺎﺭ() (Case Report • ﺍﺭﺍﻳﻪ ﺩﻗﻴﻖ ﻭ ﺣﺘﻲﺍﻟﻤﻘﺪﻭﺭ ﺗﻔﺼﻴﻠﻲ ﻭﺿﻌﻴﺖ ﻳﻚ ﻣﻮﺭﺩ ﺧﺎﺹ ﺍﺯ ﻳﻚ ﺑﻴﻤﺎﺭﻱ. – ﻣﻌﻤﻮﻻ ﺍﻳﻦ ﻣﻄﺎﻟﻌﺎﺕ ﺑﺮﺍی ﺍﻭﻟﻴﻦ ﻣﻮﺍﺭﺩ ﻳﻚ ﺑﻴﻤﺎﺭﻱ ﻳﺎ ﺑﺮﺍﻱ ﺗﻈﺎﻫﺮﺍﺕ ﺟﺪﻳﺪ ﻳﺎ ﻧﺎﺷﻨﺎﺧﺘﻪ ﻳﻚ ﺑﻴﻤﺎﺭﻱ ﺷﻨﺎﺧﺘﻪ ﺷﺪﻩ ﺍﺳﺘﻔﺎﺩﻩ ﻣﻲگﺮﺩﺩ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Case Reports • Definition - a case report consists of a description of an outcome or the condition of a patient who may be classified into a definite case category based on symptoms, signs or laboratory findings. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
گﺰﺍﺭﺵ ﻣﻮﺭﺩ )ﺑیﻤﺎﺭ( Case Report • چﻪ چیﺰی ﺭﺍ گﺰﺍﺭﺵ ﻣی کﻨیﻢ؟ ﻣﻌﺮﻓی ﻭیژگی ﻫﺎی یک ﺑیﻤﺎﺭ ﺧﺎﺹ ﺑﺮﺍﺳﺎﺱ گﺰﺍﺭﺵ یک یﺎ چﻨﺪ پﺰﺷک ﺑﺎﻟیﻨی. • ﻣﺜﺎﻝ: ﺩﺭﺳﺎﻝ 1691 یک گﺰﺍﺭﺵ ﻣﻮﺭﺩ ﺍﺯ یک ﺧﺎﻧﻢ 04 ﺳﺎﻟﻪ کﻪ پﺲ ﺍﺯ ﺷﺮﻭﻉ ﻣﺼﺮﻑ ﻗﺮﺹ پیﺸگیﺮی ﺍﺯ ﺑﺎﺭﺩﺍﺭی ﺧﻮﺭﺍکی ﺩچﺎﺭ آﻤﺒﻮﻟی ﺭیﻪ ﺷﺪﻩ ﺑﻮﺩ، ﻣﻨﺘﺸﺮ گﺮﺩیﺪ Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﺜﺎﻝ ﺩیگﺮ ﺍﺯ Case Report n یک ﺷیﺮﺧﻮﺍﺭ ) (cytogenetically normal ﻣﺒﺘﻼ ﺑﻪ گﺮﺍﻧﻮﻟﻮﺳیﺘﻮپﻨی ﺷﺪیﺪ، ﺑﺎ ﻓﺎکﺘﻮﺭ ﻣﺤﺮک کﻮﻟﻮﻧی گﺮﺍﻧﻮﻟﻮﺳیﺘی ) (GCSF ﺩﺭﻣﺎﻥ گﺮﺩیﺪ. پﺲ ﺍﺯ 11 ﻣﺎﻩ ﺩﺭﻣﺎﻥ، کﻮﺩک ﺩچﺎﺭ ﻟﻮﺳﻤی ﺣﺎﺩ ﻏیﺮﻟﻤﻔﻮﺑﻼﺳﺘیک ﺷﺪ. پیﺸﻨﻬﺎﺩ ﻓﺮﺿیﻪ: ﺍﺳﺘﻔﺎﺩﻩ ﺍﺯ ﻓﺎکﺘﻮﺭ ﻣﺤﺮک کﻮﻟﻮﻧی گﺮﺍﻧﻮﻟﻮﺳیﺘی ﺩﺭ ﺑیﻤﺎﺭﺍﻥ ﻣﺒﺘﻼ ﺑﻪ ﺍﺧﺘ ﻻﺕ ﻣﺎﺩﺭﺯﺍﺩی ﻣﻐﺰ ﺍﺳﺘﺨﻮﺍﻥ، ﻼ ﻣﻤکﻦ ﺍﺳﺖ ﺑﺎﻋﺚ ﺍیﺠﺎﺩ ﺗﻐییﺮﺍﺕ ﺑﺪﺧیﻤی ﺷﻮﺩ. )362: 621; 5991 (J Pediatr Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Important Case Reports n These all started with case reports - what study design next? Lyme Disease Legionellosis AIDS Hantavirus DES exposure EMS l-tryptophan TSS (1975) (1976) (1981) (1993) (1989) (1970) (1980) Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﺠﻤﻮﻋﻪ ﻣﻮﺭﺩ )ﺳﺮﻱ ﺑﻴﻤﺎﺭﺍﻥ( ) (Case Series • ﻧﻮﻋﻲ گﺰﺍﺭﺵ ﺑﻴﻤﺎﺭ) (Case Report ﺍﺳﺖ، ﻣﻨﺘﻬی چﻨﺪ ﺑﻴﻤﺎﺭ ﺑﺎ ﺗﻈﺎﻫﺮﺍﺕ ﺑﺎﻟﻴﻨﻲ ﻳﺎ ﺧﺼﻮﺻﻴﺎﺕ ﻣﺸﺎﺑﻪ ﺩﻳگﺮ ﻣﻮﺭﺩ ﺑﺮﺭﺳﻲ ﻗﺮﺍﺭ ﻣﻲگﻴﺮﻧﺪ. – ﺍﻳﻦ ﻣﻄﺎﻟﻌﻪ ﺩﺭ ﺍﺑﺘﺪﺍﻱ پﻴﺪﺍﻳﺶ ﻳﻚ ﺑﻴﻤﺎﺭﻱ ﻣﻲﺗﻮﺍﻧﺪ ﺭﺍﻫﻨﻤﺎﻱ ﺑﺴﻴﺎﺭ ﻣﻨﺎﺳﺒﻲ ﺑﺮﺍﻱ ﻣﻄﺎﻟﻌﻪﻫﺎﻱ ﺑﻌﺪﻱ ﺑﺎﺷﺪ. • ﻳﻜﻲ ﺍﺯ ﺑﻬﺘﺮﻳﻦ ﻧﻤﻮﻧﻪﻫﺎ ﺑﺮﺍﻱ ﺍﻳﻦ ﻧﻮﻉ ﻣﻄﺎﻟﻌﻪ، گﺰﺍﺭﺵ ﻣﺮﻛﺰ ﻛﻨﺘﺮﻝ ﺑﻴﻤﺎﺭﻳﻬﺎﻱ آﻤﺮﻳﻜﺎ ﺩﺭ ﻣﻮﺭﺩ ﺳﻨﺪﺭﻣﻲ ﺑﻮﺩ ﻛﻪ ﺑﻌﺪﻫﺎ ﺑﻪﻧﺎﻡ ﺳﻨﺪﺭﻡ ﻧﻘﺺ ﺍﻳﻤﻨﻲ ﺍﻛﺘﺴﺎﺑﻲ ) (AIDS ﻣﻌﺮﻓﻲ ﺷﺪ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﺠﻤﻮﻋﻪ ﻣﻮﺭﺩ Case Series • ﻣﺜﺎﻝ: • چﻪ چیﺰی ﺭﺍ گﺰﺍﺭﺵ ﻣی ﺩﺭ ﺳﺎﻝ 1891 ﺩﺭ ﺷﻬﺮ ﻟﺲ آﻨﺠﻠﺲ ﺩﺭ ﻃی یک ﺩﻭﺭﻩ 6 کﻨیﻢ؟ ﻣﺎﻫﻪ، 5 ﻣﺮﺩ ﻫﻤﺠﻨﺲ ﺑﺎﺯ ﺍﺯ ﻣﺸﺎﺑﻪ گﺰﺍﺭﺵ ﻣﻮﺭﺩ ﺑﺎ ﺍیﻦ ﺗﻔﺎﻭﺕ ﻗﺒﻞ ﺳﺎﻟﻢ، ﻣﺒﺘﻼ ﺑﻪ پﻨﻮﻣﻮﻧی پﻨﻮﻣﻮﺳیﺴﺘیﺲ کﺎﺭیﻨی کﻪ ﺗﻌﺪﺍﺩ ﺑیﻤﺎﺭﺍﻥ ﻣﺸﺎﻫﺪﻩ ﺷﺪﻩ ﺷﺪﻧﺪ. ﺑیﺶ ﺍﺯ یک ﻧﻔﺮ ﺍﺳﺖ. )052: 03; 1891 (MMWR Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Case Reports / Case Series
ﻫﺪﻑ ﺍﺯ ﻣﻄﺎﻟﻌﺎﺕ Case Report ﻭ Case Series n ﺗﻮﺻیﻒ ﻭﻗﻮﻉ ﺑیﻤﺎﺭیﻬﺎی ﺟﺪیﺪ n ﺗﻮﺻیﻒ پیﺎﻣﺪ یک یﺎ چﻨﺪ ﻣﻮﺭﺩ ﺍﺯ یک ﺑیﻤﺎﺭی ﻧﺎﺩﺭ یﺎ ﺗﻈﺎﻫﺮﺍﺕ ﻧﺎﺩﺭ ﺍﺯ یک ﺑیﻤﺎﺭی ﺷﺎیﻊ )ﺭﻭﺵ ﻣﻬﻤی ﺑﺮﺍی ﺗﻮﺟﻪ ﺩﺍﺩﻥ ﺟﺎﻣﻌﻪ پﺰﺷکی ﺑﻪ ﺑیﻤﺎﺭیﻬﺎی ﻏیﺮ ﻣﻌﻤﻮﻝ یﺎ ﺗﻈﺎﻫﺮﺍﺕ ﻏیﺮ ﻣﻌﻤﻮﻝ یک ﺑیﻤﺎﺭی( پیﺸﻨﻬﺎﺩ ﻓﺮﺿیﻪ ﺩﺭ ﻣﻮﺭﺩ ﺍﺭﺗﺒﺎﻁ یک ﻣﻮﺍﺟﻬﻪ یﺎ ﻋﺎﻣﻞ ﺧﻄﺮ ﺑﺎ ﻭﻗﻮﻉ یک پیﺎﻣﺪ یﺎ ﺑیﻤﺎﺭی) ﻣﻨﺒﻊ ﻏﻨی ﻓﺮﺿیﻪ ﻫﺎ( n n ﻭ ﺍﻟﺒﺘﻪ،ﻋﺎﻗﻼﻧﻪ ﺗﺮیﻦ ﻣﻮﺿﻊ: ﻋﻼﻣﺘی ﺑﺮﺍی ﺟﺴﺘﺠﻮی ﺷﻮﺍﻫﺪ ﺑیﺸﺘﺮ Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Purposes of Case Reports and Case Series Studies • To describe the occurrence of new disease entities. • To describe the outcome of a patient or patients with specific diseases. • To formulate hypotheses of the association between various exposures or risk factors and the occurrence of an outcome or disease. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﺰﺍیﺎی ﻣﻄﺎﻟﻌﺎﺕ Case Report ﻭ Case Series n ﺑﻪ ﻣﺤﻘﻖ ﺍﺟﺎﺯﻩ ﻣی ﺩﻫﺪ کﻪ ﺑیﻤﺎﺭیﻬﺎی ﺟﺪیﺪ ﺭﺍ ﺗﻮﺻیﻒ کﻨﺪ. n ﺍﻣکﺎﻥ ﺗﻮﺻیﻒ پیﺎﻣﺪﻫﺎی ﻫﻤﺮﺍﻩ ﺑﺎ ﺑیﻤﺎﺭیﻬﺎی ﻧﺎﺩﺭ ﺭﺍ ﻓﺮﺍﻫﻢ ﻣی کﻨﺪ. n چﻮﻥ ﺷﺮﺡ ﺟﺰﺀ ﺑﻪ ﺟﺰﺀ ﻣی ﺩﻫﻨﺪ ﺑﻪ ﺭﻭﺷﻦ ﺳﺎﺧﺘﻦ ﻣکﺎﻧیﺰﻣﻬﺎی ﺑیﻤﺎﺭی ﻭ ﺩﺭﻣﺎﻥ کﻤک ﻣی کﻨﺪ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Advantages of Case Reports and Case series • Allows for the description of new disease processes. • Allows for the description of outcomes associated with rare diseases. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻌﺎیﺐ ﻭ ﻣﺤﺪﻭﺩیﺘﻬﺎی ﻣﻄﺎﻟﻌﺎﺕ Case Report ﻭ Case Series n ﺗﻌییﻦ ﻓﺮﺍﻭﺍﻧی ﻭﻗﻮﻉ ﺑیﻤﺎﺭی، ﻣﻤکﻦ ﻧیﺴﺖ. n ﻧﺒﺎیﺪ ﻣﺒﻨﺎی ﺗﻐییﺮ ﺩﺭ ﺭﻭﺵ ﻃﺒﺎﺑﺖ ﻗﺮﺍﺭ گیﺮﻧﺪ. چﻮﻥ ﺣﺘی ﻭﻗﺎیﻊ ﻧﺎﺩﺭ ﻧیﺰ ﺑﻪ ﺣکﻢ ﺷﺎﻧﺲ ﻣﻤکﻦ ﺍﺳﺖ ﺑﺎﻫﻢ ﺭﻭی ﺩﻫﻨﺪ. n ﻧﻤی ﺗﻮﺍﻧﺪ ﺭﺍﺑﻄﻪ ﻋﻠیﺘی ﺑیﻦ ﻣﻮﺍﺟﻬﻪ )ﺭیﺴک ﻓﺎکﺘﻮﺭ( ﻭ پیﺎﻣﺪ )یﺎ ﺑیﻤﺎﺭی( ﺭﺍ ﺑﺮﺭﺳی کﻨﺪ. ﺑﻪ ﻋﺒﺎﺭﺕ ﺩیگﺮ ﺍﻣکﺎﻥ آﺰﻣﻮﻥ ﻓﺮﺿیﻪ ﻭﺟﻮﺩ ﻧﺪﺍﺭﺩ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Disadvantages/Limitations of Case Report & Case Series • Impossible to determine disease frequency. • Cannot establish causality between exposures or risk factors and disease outcome. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Case Reports / Case Series • Case reports are susceptible to bias. • NEVER use case reports to make treatment decisions. • Case reports are interesting but should not be considered when critically appraising topics Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻄﺎﻟﻌﺎﺕ ﻣﻘﻄﻌﻲ ) (Cross-sectional studies ﻣﻄﺎﻟﻌﺎﺗﻲ ﻫﺴﺘﻨﺪ ﻛﻪ ﺑﻴﺸﺘﺮ ﺑﻪ ﻣﻨﻈﻮﺭ ﺗﻮﺻﻴﻒ ﻳﻚ ﻳﺎ چﻨﺪ پﺪﻳﺪﻩ ﺳﻼﻣﺘﻲ ﺩﺭ ﺯﻣﺎﻥ ﻭ ﻣﻜﺎﻥ ﺗﻌﺮﻳﻒ ﺷﺪﻩﺍﻱ ﺍﻧﺠﺎﻡ ﻣﻲگﺮﺩﻧﺪ. ﺍﻳﻦ ﻣﻄﺎﻟﻌﺎﺕ ﻣﻌﻤﻮﻻ ﺑﺮ ﺭﻭﻱ گﺮﻭﻫﻲ ﺗﻌﺮﻳﻒﺷﺪﻩ ﻭ ﻣﺸﺨﺺ ﺍﻧﺠﺎﻡ ﻣﻲگﺮﺩﺩ. ﺑﺮﺭﺳﻲ ﻭﺿﻌﻴﺖ ﺳﻼﻣﺖ ﺑﻴﻨﺎﻳﻲ ﺩﺭ ﺳﺎﻛﻨﻴﻦ ﺷﻬﺮ ﺗﻬﺮﺍﻥ ﺩﺭ ﺳﺎﻝ 1831 Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﺧﺼﻮﺻﻴﺎﺕ ﻣﻄﺎﻟﻌﺎﺕ ﻣﻘﻄﻌﻲ • ﺍﻳﻦ ﻣﻄﺎﻟﻌﺎﺕ ﻣﻌﻤﻮﻻ ﺑﺮ ﺭﻭﻱ ﻧﻤﻮﻧﻪﺍﻱ ﺗﺼﺎﺩﻓﻲ ﺍﺯ گﺮﻭﻩ ﺗﻌﺮﻳﻒﺷﺪﻩ ﺍﺻﻠﻲ ﺍﻧﺠﺎﻡ ﻣﻲگﻴﺮﺩ. • ﺍﻳﻦ ﻣﻄﺎﻟﻌﺎﺕ ﺗﻮﺍﻧﺎﻳﻲ ﺗﻌﻴﻴﻦ ﻣﻴﺰﺍﻥ ﺷﻴﻮﻉ ﻧﻘﻄﻪﺍﻱ ﻳﻚ پﺪﻳﺪﻩ ﺭﺍ ﺩﺭ ﺟﺎﻣﻌﻪ ﺩﺍﺭﻧﺪ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Cross-sectional studies • Research questions usually have the following general form: – “Is Factor A associated with Factor B? ” – "What is the prevalence of Disease X or Factor Y in a given population? " – "How many people in the population have Disease X or Factor Y? " Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی Cross-sectional • • ﺑﺮﺭﺳی ﺍﻓﺮﺍﺩ یک ﺟﻤﻌیﺖ ) ﻫﺮ ﻓﺮﺩ ﻓﻘﻂ یک ﺑﺎﺭ ﺑﺮﺭﺳی ﻣی ﺷﻮﺩ( ﻣﺘﺪﺍﻭﻟﺘﺮ ﺍﺯ ﺳﺎیﺮ ﻣﻄﺎﻟﻌﺎﺕ ﺍﺳﺖ ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی کﻪ ﺑﻪ ﻋﻨﻮﺍﻥ ﻣﻄﺎﻟﻌﻪ » ﺷیﻮﻉ « ﻧیﺰ ﺧﻮﺍﻧﺪﻩ ﻣی ﺷﻮﺩ، ﻣﻌﻤﻮﻻ ﺷﺎﻣﻞ یک ﻧﻤﻮﻧﻪ گیﺮی ﺗﺼﺎﺩﻓی ﺍﺯ ﺟﻤﻌیﺖ ﻫﺪﻑ ﺍﺳﺖ. ﺩﺭ ﻣﺮﺣﻠﻪ ﺑﻌﺪ ﻓﺮﺍﻭﺍﻧی ﺑیﻤﺎﺭی ﻭ ﻭﺿﻌیﺖ ﻣﻮﺍﺟﻬﻪ ﻫﺎی ﻓﻌﻠی یﺎ ﻗﺒﻠی ﺍﻓﺮﺍﺩ ﻭ ﺳﺎیﺮ ﻣﺘﻐیﺮﻫﺎی ﻣﻮﺭﺩ ﻋﻼﻗﻪ ﻣﺤﻘﻖ ﺩﺭ ﺍیﻦ ﻧﻤﻮﻧﻪ ﺑﺮﺭﺳی ﻣی ﺷﻮﺩ. Cross-sectional study=Prevalence study Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﺗﻌﺮیﻒ ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی Cross-sectional ﻣﻮﺍﺟﻬﻪ ﻭ پیﺎﻣﺪ ﺑﻪ ﻃﻮﺭ ﻫﻢ ﺯﻣﺎﻥ، ﺩﺭ ﻫﺮ ﻓﺮﺩ، ﺩﺭ یک ﻧﻘﻄﻪ ﺍﺯ ﺯﻣﺎﻥ )ﻣﺎﻧﻨﺪ یک ﻋکﺲ ﻓﻮﺭی( ﺍﻧﺪﺍﺯﻩ گیﺮی ﻣی ﺷﻮﻧﺪ. ONE SLICE IN TIME Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Cross-Sectional Study Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Cross-Sectional Study Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Cross-sectional studies Disease Status Yes Exposure Status No Total Yes a b a +b No c d c +d a +c b +d N Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Cross-sectional studies CHD Yes Physically Active No Total Yes 3 87 90 No 14 75 89 17 162 Dr Seyyed Alireza Moravveji MD Community Medicine specialist 179
کﺎﺭﺑﺮﺩ ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی • ﺷﻨﺎﺳﺎیی ﻭ ﺗﻮﺻیﻒ ﻓﺮﺍﻭﺍﻧی ﻣﺸکﻼﺕ ﻣﺮﺑﻮﻁ ﺑﻪ ﺳﻼﻣﺘی ﺩﺭ ﺟﺎﻣﻌﻪ. • ﺟﻤﻊ آﻮﺭی ﺍﻃﻼﻋﺎﺕ ﺑﺮﺍی ﺑﺮﻧﺎﻣﻪ ﺭیﺰی، ﻣﺎﻧﻨﺪ: ﻣﻄﺎﻟﻌﺎﺕ ﺭﺿﺎیﺖ ﺳﻨﺠی، ﻧیﺎﺯﺳﻨﺠی، پﻮﺷﺶ ﺑﺮﻧﺎﻣﻪ ﻫﺎ. • ﺍﺭﺯیﺎﺑی ﻣیﺰﺍﻥ ﺑﻬﺮﻩ ﻣﻨﺪی ﺍﺯ ﺧﺪﻣﺎﺕ ﺑﻬﺪﺍﺷﺘی ﺩﺭﻣﺎﻧی. • پﺎیﺶ ﺭﻭﻧﺪﻫﺎی ﻣﺮﺑﻮﻁ ﺑﻪ ﺳﻼﻣﺖ ﻭ ﺑیﻤﺎﺭی ﺩﺭ ﺟﺎﻣﻌﻪ ﺑﺎ ﺍﻧﺠﺎﻡ ﻣﻄﺎﻟﻌﺎﺕ ﻣﻘﻄﻌی ﻣکﺮﺭ – ﻣﺎﻧﻨﺪ ”ﻃﺮﺡ ﺳﻼﻣﺖ ﻭ ﺑیﻤﺎﺭی“ یﺎ "NHNES ﺑﺮﺭﺳﻲ ﻣﻠﻲ ﻣﻌﺎﻳﻨﻪ ﺑﻬﺪﺍﺷﺘﻲ ﻭ ﺗﻐﺬﻳﻪ ﺍﻱ” ) (National Health and Nutrition Examination Survey ﺑﺎ ﻧﻤﻮﻧﻪ ﺑﻪ ﺩﻗﺖ ﺍﻧﺘﺨﺎﺏ ﺷﺪﻩ ﻣﻌﻑ ﺟﻤﻌﻴﺖ ﺍﻳﺎﻻﺕ ﻣﺘﺤﺪﻩ ﻣﺼﺎﺣﺒﻪ ﻭ ﻣﻌﺎﻳﻨﻪ ﺑﻪ ﻋﻤﻞ آﻤﺪ. • پیﺸﻨﻬﺎﺩ ﻓﺮﺿیﻪ ﻫﺎی ﺍﺗیﻮﻟﻮژیک ﺩﺭ ﻣﻮﺭﺩ ﺍﺭﺗﺒﺎﻁ ﻣﻮﺍﺟﻬﻪ ﺑﺎ ﺑیﻤﺎﺭی. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﺰﺍیﺎی ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی • ﻧﺴﺒﺘ ﺍﺭﺯﺍﻥ ﻭ آﺴﺎﻥ ﺍﺳﺖ، ﺑﻪ ﻭیژﻪ ﺍﺯ ﺍیﻦ ﺟﻨﺒﻪ کﻪ ﺍﺣﺘیﺎﺝ ﺑﻪ پیگیﺮی ﻧﺪﺍﺭﺩ. • ﺗﺨﻤیﻨی ﺍﺯ ﺷیﻮﻉ ﺑیﻤﺎﺭی ﻭ ﻣﻮﺍﺟﻬﻪ ﺩﺭ ﺟﺎﻣﻌﻪ ﻫﺪﻑ ﺑﻪ ﺩﺳﺖ ﻣیآیﺪ. • ﻫیچکﺲ ﺑﺎ یک ﻋﺎﻣﻞ ﺧﻄﺮ ﺍﺣﺘﻤﺎﻟی ﻣﻮﺍﺟﻬﻪ ﺩﺍﺩﻩ ﻧﻤیﺷﻮﺩ یﺎ ﺍﺯ یک ﻋﺎﻣﻞ ﻣﻔیﺪ ﺍﺣﺘﻤﺎﻟی ﻣﺤﺮﻭﻡ ﻧﻤیگﺮﺩﺩ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Cross-sectional Study: Pluses + Prevalence (not incidence) + Fast/Inexpensive - no waiting! + No loss to follow up + Associations can be studied
Cross-sectional study: minuses - Cannot determine causality • ACE inhibitor use and hospitalization rates among those with heart failure time
Cross-sectional study: minuses - Cannot determine causality - Cannot study rare outcomes
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻌﺎیﺐ ﻭ ﻣﺤﺪﻭﺩیﺘﻬﺎی ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی • ﺑﺮﺍی آﺰﻣﻮﻥ ﻓﺮﺿیﻪ یﺎ ﺑﺮﻗﺮﺍﺭی ﺍﺭﺗﺒﺎﻁ ﻋﻠﺖ ﻭ ﻣﻌﻠﻮﻟی ﺿﻌیﻒ ﺍﺳﺖ، چﻮﻥ ﻭﺿﻌیﺖ ﻣﻮﺍﺟﻬﻪ ﻭ پیﺎﻣﺪ ﻫﻢ ﺯﻣﺎﻥ ﺗﻌییﻦ ﻣیگﺮﺩﺩ ﻭ ﺗﻘﺪﻡ ﻭ ﺗﺎﺧﺮ ) ) (temporality ﺗﺮﺗیﺐ ﺯﻣﺎﻧی( آﻨﻬﺎ ﻣﺸﺨﺺ ﻧیﺴﺖ. ﺍﻣکﺎﻥ ﺭﺍﺑﻄﻪ ﻋﻠیﺘی ﻣﻌکﻮﺱ ) (reverse causality ﻧیﺰ ﻭﺟﻮﺩ ﺩﺍﺭﺩ. • ﻣﻌﻤﻮﻻ ﺧﻄﺮ ﺳﻮگیﺮی ﺍﻧﺘﺨﺎﺏ ﺑﻪ ﻋﻠﺖ ﻋﺪﻡ پﺎﺳﺦ ﺩﻫی کﺎﻣﻞ ﻧﻤﻮﻧﻪﻫﺎ ) (low response rate ﻭﺟﻮﺩ ﺩﺍﺭﺩ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻌﺎیﺐ ﻭ ﻣﺤﺪﻭﺩیﺘﻬﺎی ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی )ﺍﺩﺍﻣﻪ( • ﺑیﻤﺎﺭﺍﻧی کﻪ ﺩﺭﺍﺛﺮ ﺑیﻤﺎﺭی ﺯﻭﺩ ﻣی ﻣیﺮﻧﺪ؛ یﺎ ﺍﻓﺮﺍﺩی کﻪ ﺷﻮﺍﻫﺪ ﻧﺸﺎﻥ ﺩﻫﻨﺪﻩ ﻣﻮﺍﺟﻬﻪ، ﺯﻭﺩ ﺩﺭ آﻨﻬﺎ ﻣﺤﻮ ﻣی ﺷﻮﺩ یﺎ آﻦ ﺭﺍ ﺑﻪ ﺧﺎﻃﺮ ﻧﻤی آﻮﺭﻧﺪ ﻣﻤکﻦ ﺍﺳﺖ ﺑﻪ ﺣﺴﺎﺏ ﻧیﺎیﻨﺪ. – ﺑﺮﺍﻱ ﻣﺜﺎﻝ، ﺷﻴﻮﻉ ﺍﻓﺴﺮﺩگﻲ ﺷﺪﻳﺪ ﻧﻪ ﺗﻨﻬﺎ ﺗﺤﺖ ﺗﺎﺛﻴﺮ ﺑﺮﻭﺯ آﻦ ﺍﺳﺖ، ﺑﻠﻜﻪ ﺗﺤﺖ ﺗﺎﺛﻴﺮ ﻣﻴﺰﺍﻥ ﺧﻮﺩﻛﺸﻲ ﻭ پﺎﺳﺦ ﺑﻪ ﺩﺭﻣﺎﻥ ﻣﺒﺘﻼﻳﺎﻥ ﻧﻴﺰ ﻣﻲ ﺑﺎﺷﺪ. • ﺩﺭ ﻣﻮﺭﺩ ﺑیﻤﺎﺭیﻬﺎی ﻧﺎﺩﺭ ﻣﺸکﻞ ﺍﺳﺖ ﻭ ﻣﻤکﻦ ﺍﺳﺖ ﻋﻤﻠی ﻧﺒﺎﺷﺪ. – ﻣﺜﻼ ﻳﻚ ﻣﻄﺎﻟﻌﺔ ﻣﻘﻄﻌﻲ ﺑﺮﺍﻱ ﻳﺎﻓﺘﻦ ﺗﻨﻬﺎ ﻳﻚ ﻣﻮﺭﺩ ﺳﺮﻃﺎﻥ ﻣﻌﺪﻩ ﺩﺭ ﻣﺮﺩﺍﻥ 94ـ54 ﺳﺎﻟﻪ ﺑﻪ ﺗﻘﺮﻳﺐ 00001 ﺷﺮﻛﺖ ﻛﻨﻨﺪﻩ ﻻﺯﻡ ﺧﻮﺍﻫﺪ ﺩﺍﺷﺖ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻌﺎیﺐ ﻭ ﻣﺤﺪﻭﺩیﺘﻬﺎی ﻣﻄﺎﻟﻌﻪ ﻣﻘﻄﻌی )ﺍﺩﺍﻣﻪ( • گﺮﻭﻩ ﺑﻨﺪی ﺍﻓﺮﺍﺩ ﺑﺮﺣﺴﺐ ﻭﺿﻌیﺖ ﻣﻮﺍﺟﻬﻪ یﺎ پیﺎﻣﺪ ﻣﻤکﻦ ﺍﺳﺖ ﺍیﺠﺎﺩ گﺮﻭﻩ ﻫﺎی ﺑﺎ ﺣﺠﻢ ﻧﻤﻮﻧﻪ ﻧﺎﻣﺴﺎﻭی کﻨﺪ، کﻪ ﺍیﻦ ﺍﻣﺮ ﺑﺎﻋﺚ ﺍﺯ ﺩﺳﺖ ﺭﻓﺘﻦ کﺎﺭآﻤﺪی آﻤﺎﺭی ) (statistical efficiency ﻣیﺸﻮﺩ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﺧﻄﺮﺍﺕ ﻭ ﺧﻄﺎﻫﺎﻱ ﻧﺎﺷﻲ ﺍﺯ ﻣﻄﺎﻟﻌﺎﺕ ﻣﻘﻄﻌﻲ ﺗﺤﻠﻴﻠﻲ • ﺍﺯ آﻦﺟﺎﻳﻲ ﻛﻪ ﺍﻳﻦ ﻣﻄﺎﻟﻌﺎﺕ ﺑﺎ ﺍﻓﺮﺍﺩﻱ ﺳﺮﻭﻛﺎﺭ ﺩﺍﺭﻧﺪ ﻛﻪ ﻳﻚ ﻭﺿﻌﻴﺖ ﺳﻼﻣﺘﻲ ﺭﺍ ﺩﺍﺭﻧﺪ، ﻧﻪ ﺍﻓﺮﺍﺩﻱ ﻛﻪ ﻳﻚ ﻭﺿﻌﻴﺖ ﺳﻼﻣﺘﻲ ﺭﺍ پﻴﺪﺍ ﻣﻲﻛﻨﻨﺪ، ﺩﺭ ﺗﺤﻠﻴﻞ ﻋﻮﺍﻣﻞ ﻣﺮﺗﺒﻂ ﺑﺎ پﻴﺪﺍﻳﺶ ﻳﻚ ﻭﺿﻌﻴﺖ ﺳﻼﻣﺘﻲ ﺑﺎﻳﺪ ﺧﻄﺮ ﺳﻮگﺮﺍیی ﺍﻧﺘﺨﺎﺏ ) (Selection Bias ﺭﺍ ﺑﻪﺧﺎﻃﺮ ﺩﺍﺷﺖ. • ﺍﺯ آﻦﺟﺎﻳﻲ ﻛﻪ ﺩﺭ ﺍﻳﻦ ﻣﻄﺎﻟﻌﺎﺕ ﺗﻮﺍﻟﻲ ﺯﻣﺎﻧﻲ ﺑﻴﻦ ﻳﻚ ﻭﺿﻌﻴﺖ ﺳﻼﻣﺘﻲ ﻭ ﻋﻮﺍﻣﻞ ﻣﺮﺗﺒﻂ ﺑﺎ آﻦ ﺩﺭ ﺑﺴﻴﺎﺭﻱ ﻣﻮﺍﺭﺩ ﺩﻳﺪﻩ ﻧﻤﻲﺷﻮﺩ، ﺗﺤﻠﻴﻞ ﻋﻮﺍﻣﻞ ﻣﺮﺗﺒﻂ ﺑﺎﻳﺪ ﺑﺎ ﻣﺤﺎﻓﻈﻪﻛﺎﺭﻱ ﺑﺴﻴﺎﺭ ﺯﻳﺎﺩ ﺍﻧﺠﺎﻡ گﺮﺩﺩ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﻣﻄﺎﻟﻌﻪ ﺍکﻮﻟﻮژیک ) ﺑﻮﻡ ﺷﻨﺎﺧﺘی( )یﺎ ﻫﻤﺒﺴﺘگی (Correlational study • ﻭﺍﺣﺪ ﻣﻄﺎﻟﻌﻪ ﺩﺭ ﺍیﻦ ﺣﺎﻟﺖ » ﺟﺎﻣﻌﻪ « ﺍﺳﺖ، ﻧﻪ » ﻓﺮﺩ «. • ﺍﺭﺗﺒﺎﻁ ﺑیﻦ ﺳﻄﺢ ﻣﻮﺍﺟﻬﻪ ﻭ ﻓﺮﺍﻭﺍﻧی ﺑیﻤﺎﺭی ﺭﺍ ﺩﺭ ﺑیﻦ ﺗﻌﺪﺍﺩی ﺍﺯ ﺟﻮﺍﻣﻊ ﺑﺮﺭﺳی ﻭ ﻣﻘﺎیﺴﻪ ﻣی کﻨﺪ. • ﻧﻘﻄﻪ ﻗﻮﺕ آﻦ ﺩﺭ ﺗﻌییﻦ ﺍﺭﺗﺒﺎﻁ ﺑیﻤﺎﺭی ﺑﺎ ﻣﺘﻐیﺮﻫﺎیی ﺍﺳﺖ کﻪ ﺩﺭ ﺳﻄﺢ ﺟﺎﻣﻌﻪ ﺑیﺸﺘﺮ ﻣﻌﻨی پیﺪﺍ ﻣیکﻨﻨﺪ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Studies using groups as units of observation • ECOLOGIC STUDIES – To assess the correlation between a presumed risk factor and an outcome, mean values of the outcome (e. g. , rate, mean) are plotted against mean values of the factor (e. g. , average per capita fat intake), using groups as units of observation – Groups can be defined by place (geographical comparisons) or time (temporal trends).
Ecologic Studies • In an ecological study, variables may be measured on individuals, although comparisons are always between groups, never between individuals • Results are extremely prone to confounding (bias) 45
Ecologic Studies • Research questions usually have the following general form: – Is the prevalence (or average level) of Factor X associated with the prevalence or incidence of Disease (or Factor) Y? 46
Ecologic Studies General question: ◦ Is the mineral content of consumed water associated with coronary heart disease? Specific question: ◦ Among men in England Wales is the calcium content of a community's water supply associated with mortality due to coronary heart disease? 47
Ecologic Studies Independent variable: ◦ Calcium content of the municipal water supply Dependent variable: ◦ Cardiovascular mortality rate of the community Target population: ◦ Not stated, industrialized nations is implied Study population: ◦ 61 towns in England Wales 48
A plot of the population of Oldenburg at the end of each year against the number of storks observed in that year, 1930 -1936. Ornitholigische Monatsberichte 1936; 44(2)
Relation between sodium (Na) excretion and age increase in systolic blood pressure (SBP) in centers in the INTERSALT cohort* *Elliot, in Marmot and Elliot (eds. ): Coronary Heart Disease Epidemiology, Oxford, 1992, pp. 166 -78.
Ecologic studies are the design of choice in certain situations: • When the level of inference of interest is at the population level – Food availability (e. g. , Goldberger et al: Public Health Rep 1916; 35: 2673 -714). – SES inequality and health • When the variability of exposure within the population is limited – Salt intake and hypertension (Elliot, 1992) – Fat intake and breast cancer (Wynder et al, 1997)
Systolic blood pressure (mm Hg) Hypothetical data on individuals from a World-wide population Strong positive (linear) association Usual daily salt intake
Systolic blood pressure (mm Hg) SBP (mm Hg) Hypothetical data on individuals from a World-wide population Individuals from country A Usual daily salt intake No association Usual daily salt intake
Systolic blood pressure (mm Hg) Hypothetical data on individuals from a World-wide population Usual daily salt intake Country A Country B Country C Country D Country E Country F Country G
Hypothetical ecologic data from 7 countries Mean systolic blood pressure (mm Hg) Country A Country B Country C Country D Country E Country F Country G Mean usual daily salt intake Strong positive (linear) association
ﻣﻌﺎیﺐ ﻣﻄﺎﻟﻌﻪ ﺍکﻮﻟﻮژیک 1. ) ecological fallacy ﻣﻐﺎﻟﻄﻪ ﺍکﻮﻟﻮژیک(: ﻣﻤکﻦ ﺍﺳﺖ ﺍﺭﺗﺒﺎﻃی کﻪ ﺩﺭ ﺳﻄﺢ ﺟﺎﻣﻌﻪ ﺑیﻦ ﻣﻮﺍﺟﻬﻪ ﻭ پیﺎﻣﺪ ﺩیﺪﻩ ﻣیﺷﻮﺩ، ﺩﺭ ﺳﻄﺢ ﻓﺮﺩ ﻭﺟﻮﺩ ﻧﺪﺍﺷﺘﻪ ﺑﺎﺷﺪ. – ﻣﺸﺎﻫﺪﻩ ﺍﺭﺗﺒﺎﻁ ﻣﺜﺒﺖ ﺑیﻦ ﻣیﺰﺍﻥ ﺧﻮﺩکﺸی ﻭ ﺩﺭﺻﺪ پﺮﻭﺗﺴﺘﺎﻧﻬﺎ ﺩﺭ ﺟﻮﺍﻣﻊ ﻣﺨﺘﻠﻒ: – ﺩﺭ ﻭﺍﻗﻊ کﺎﺗﻮﻟیکﻬﺎیی کﻪ ﺩﺭ ﺍﻗﻠیﺖ ﻗﺮﺍﺭ ﻣیگﺮﻓﺘﻨﺪ ﺑیﺸﺘﺮ ﺧﻮﺩکﺸی ﻣیکﺮﺩﻧﺪ، ﻧﻪ پﺮﻭﺗﺴﺘﺎﻧﻬﺎ! 2. ﻣیﺎﻧگیﻦ ﻣﺮﺑﻮﻁ ﺑﻪ ﺟﺎﻣﻌﻪ ﺍﺳﺖ )ﺩﺭ ﻣﻮﺭﺩ ﻓﺮﺩ ﻧﻤیﺗﻮﺍﻧیﻢ ﻗﻀﺎﻭﺕ کﻨیﻢ( ﻭ ﻓﻘﻂ ﺩیﺪی کﻠی ﺩﺭ ﻣﻮﺭﺩ ﺟﺎﻣﻌﻪ ﻣیﺩﻫﺪ. Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ﺍﺭﺗﺒﺎﻁ ﺑیﻦ ﻣیﺰﺍﻥ ﻣﺼﺮﻑ چﺮﺑی ﺑﺎ ﺳﺮﻃﺎﻥ پﺴﺘﺎﻥ ﺑﺮ ﺣﺴﺐ کﺸﻮﺭ USA Incidence Ratio per 100, 000 Women 250 Switzerland Canada 200 Fed. Repub. Of Germany Italy Israel Sweden France Denmark New Zealand Australia 150 UK Norway Finland Yugoslavia 100 Spain Poland Romania Hong Kong Hungary 50 Japan 0 0 600 800 1000 1200 1400 Prentice RL, Kakar F, Hursting S, et al: Aspects of Per Capita Supply of Fat Calories Dr Seyyed Alireza Moravveji MD the rationale for the Women’s Health Trial. J Natl Community Medicine specialist Cancer Inst 80: 802 -814, 1988. ) 1600
آیﺎ ﺍﺭﺗﺒﺎﻃی ﺑیﻦ ﻣﺼﺮﻑ چﺮﺑی ﻭ ﺳﺮﻃﺎﻥ پﺴﺘﺎﻥ ﻭﺟﻮﺩ ﺩﺍﺭﺩ؟ • ﺩﺭ ﻧﻤﻮﺩﺍﺭ ﻣی ﺑیﻨیﻢ کﻪ: – ﺑﺎ ﺑﺎﻻ ﺭﻓﺘﻦ ﻣﺘﻮﺳﻂ ﻣﺼﺮﻑ چﺮﺑی، ﻣیﺰﺍﻥ ﺑﺮﻭﺯ ﺳﺮﻃﺎﻥ پﺴﺘﺎﻥ ﺍﻓﺰﺍیﺶ ﻣی یﺎﺑﺪ • چﻪ ﺍﺷکﺎﻟی ﺩﺭ ﺍیﻦ ﺩﺍﺩﻩ ﻫﺎ ﻭﺟﻮﺩ ﺩﺍﺭﺩ؟ • ﻣﺸکﻞ ﺍیﻦ ﺍﺳﺖ: !ecological fallacy Dr Seyyed Alireza Moravveji MD Community Medicine specialist
ecological fallacy • ﻧﺴﺒﺖ ﺩﺍﺩﻥ ﺻﻔﺎﺕ ﺑﻪ ﺍﻓﺮﺍﺩ یک گﺮﻭﻩ، ﺩﺭ ﺣﺎﻟی کﻪ ﺍیﻦ ﺻﻔﺎﺕ ﺑﻪ ﻋﻨﻮﺍﻥ ﻓﺮﺩ ﺑﻪ آﻨﻬﺎ ﺗﻌﻠﻖ ﻧﺪﺍﺭﺩ. • ﺩﺭ کﺸﻮﺭﻫﺎیی کﻪ ﻣﺼﺮﻑ چﺮﺑی ﺑﺎﻻﺗﺮ ﺍﺳﺖ ﺑﺮﻭﺯ ﺳﺮﻃﺎﻥ پﺴﺘﺎﻥ ﻧیﺰ ﺑیﺸﺘﺮ ﺍﺳﺖ، ﺍﻣﺎ ﻧﻤی ﺩﺍﻧیﻢ کﻪ آیﺎ ﺍﻓﺮﺍﺩ ﻣﺒﺘﻼ ﺑﻪ ﺳﺮﻃﺎﻥ پﺴﺘﺎﻥ، ﻫﻤﺎﻥ ﺍﻓﺮﺍﺩی ﻫﺴﺘﻨﺪ کﻪ چﺮﺑی ﺑیﺸﺘﺮ ﻣﺼﺮﻑ ﻣی کﻨﻨﺪ یﺎ ﺧیﺮ؟ Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Ecological fallacy “The bias that may occur because an association observed between variables on population levels does no necessarily represent the association that exists at the individual level. ” Last: Dictionary of Epidemiology, 1995 Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Example of ecological bias* Population A $10. 5 K $34. 5 K $28. 5 K $12. 2 K $45. 6 K $17. 5 K $19. 8 K Traffic injuries: 4/7=47% Mean income: $23. 940 Population B $12. 5 K $32. 5 K $24. 3 K $10. 0 K $14. 3 K $38. 0 K $26. 4 K Traffic injuries: 3/7=43% Mean income: $22. 430 Population C $28. 7 K $30. 2 K $13. 5 K $23. 5 K Mean income: $21. 410 *Based on: Diez-Roux, Am J Public Health 1998; 88: 216. $10. 8 K $22. 7 K $20. 5 K Traffic injuries: 2/7=29%
Ecologic analysis Higher income is associated with higher injury rate Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Example of ecological bias* Population A $10. 5 K $34. 5 K $28. 5 K $12. 2 K $45. 6 K $17. 5 K $19. 8 K Traffic injuries: 4/7=47% Mean income: $23, 940 Population B $12. 5 K $32. 5 K $24. 3 K $10. 0 K $14. 3 K $38. 0 K $26. 4 K Traffic injuries: 3/7=43% Mean income: $22, 430 Population C $28. 7 K $30. 2 K Mean income: $21, 410 $13. 5 K $23. 5 K $10. 8 K Dr Seyyed Alireza Moravveji MD Community Medicine specialist *Based on: Diez-Roux, Am J Public Health 1998; 88: 216. $22. 7 K $20. 5 K Traffic injuries: 2/7=29%
Ecologic analysis Higher income is associated with higher injury rate Individual-based analysis Injury cases have lower mean income than non cases Dr Seyyed Alireza Moravveji MD Community Medicine specialist
• Which of the two levels of inference is wrong? – Concluding that high income is a risk factor for injuries (based on the ecologic data) is subject to ecologic fallacy. – BUT … concluding that, because injury cases tend to have lower income, communities with higher average income should have lower injury rates is also wrong! • The real problem is cross-level reference* – Using ecologic data to make inference at the individual level (ecologic fallacy). – Or using the individual data to make inferences at the group (population level). • When used to make inferences at the proper level, both approaches might be right. *Morgenstern: Ann Rev Public Health 1995; 16: 61 -81.
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Data 2 Observing 1 3 -4 Information 10 Epidemiological Sequence Cycle 9 5 7 6 8 Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Data 2 Observing 1 3 -4 Information 10 Epidemiological Sequence Cycle 9 Intelligence Developing the 5 Hypothesis 7 6 8 Dr Seyyed Alireza Moravveji MD Community Medicine specialist Testing the Hypothesis
Step 6: Analytic studies: -Observational Studies Case –control studies Cohort studies - Interventional studies Clinical trials . Dr Seyyed Alireza Moravveji MD Community Medicine specialist
Observing 1 Data 2 3 -4 Information 10 Epidemiological Sequence Cycle 9 8 Intelligence Developing the 5 Hypothesis 7 Making Scientific inferences Dr Seyyed Alireza Moravveji MD Community Medicine specialist 6 Testing the Hypothesis
A S K H A N N H H N K N T N S K N K H N T H N S H H K K N K T S H A H T T S S N A H T K H Dr Seyyed Alireza Moravveji MD Community Medicine specialist N A N T H S N K K N N N H T S K K S T A N T K N S T K
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