an the primary diagnosis responsible for hospitalization \[[@CR59]\]; we could no discard misclassification in our dataset.

Conclusions {#Sec12}
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Cold spells but not heatwaves increased emergency hospitalizations due to cardiovascular diseases from 2006 through 2013 in a Mediterranean region (Catalonia, Southern Europe). The impact of cold spells showed a stronger effect when the exposure encompassed the duration of the cold spell and a lagged period of 3 or 7 days. Moreover, we observed different impacts depending on the cardiovascular outcome, since coronary heart disease did not significantly increase emergency hospitalization during cold spells. Our findings might be helpful to encourage the development of a Cold Health Action Plan, to complement the already existing Heatwaves Action Plan \[[@CR48]\] implemented by the regional government in Catalonia.

Additional files
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 {#Sec13}

Additional file 1:Classification of Diseases codes (ICD, Ninth and Tenth revision). Description of data: ICD-9 and ICD10 used to define the study outcome. (DOCX 13 kb) Additional file 2:Sensitivity analyses to assess the effect of cold spells on cardiovascular hospitalizations. Description of data: Incident rate ratios (IRR) for cardiovascular emergency hospitalization considering three exposures: cold spells, cold spells and the next 3 days, and cold spells and the next 7 days. Models adjusted by age, age and forthnight, and survivor analyses are shown. Results are shown stratified by gender, age groups and cardiovascular (CV) event type. ^a^Age groups used for adjustment in models restricted to population \<65 years old: 18--35, 36--55; 56--64. ^b^Age groups used for adjustment in models restricted to population ≥65 years old; 65--70, 71--75, 76--80, \>80. ^c^ Survivor Analyses: individuals whose follow-up ended within 90 days of their cardiovascular event were excluded. (PDF 37 kb) Additional file 3:Sensitivity analyses to assess the effect of heatwaves on cardiovascular hospitalizations. 