The impact of ai r q ua l ity index (AQI) and par tic ulate mat ter 2.5 (PM ) c oncen tration on the incid en ce of st roke i n Karachi, Pakist an : A bidirec tion al cohor t st ud y.

Stroke subtype and onset time had no significant association with AQI readings or PM2.5 concentrations in the three days preceding stroke onset.

• The study examined air quality data for the three days preceding stroke onset for each patient.
• No significant association was found between stroke type and AQI or PM2.5 at days 1, 2, and 3 (p>0.05).
• Both ischaemic and haemorrhagic stroke subtypes were included in the analysis.
• Stroke onset time was also not significantly associated with air quality measures.

The study population consisted of 228 newly hospitalised stroke patients with a mean age of 62.15±14.20 years.

• Of the 228 patients, 149 (65.4%) were males and 79 (34.6%) were females.
• The overall mean age was 62.15±14.20 years.
• The study was conducted at the Neurology Department of Liaquat National Hospital, Karachi.
• The study period ran from August 10, 2022, to February 5, 2024.
• Only newly hospitalised patients with acute onset of stroke were included.

Males exhibited a heightened propensity for experiencing ischaemic strokes compared to females.

• The odds ratio for males experiencing ischaemic strokes compared to females was 1.179.
• This association was not statistically significant (p=0.606).

Individuals with ischaemic heart disease demonstrated an elevated risk of suffering ischaemic strokes compared to those without the comorbidity.

• The odds ratio for ischaemic stroke in patients with ischaemic heart disease was 2.986.
• This association approached but did not reach conventional statistical significance (p=0.051).

Air pollutant data was sourced from a Swiss website providing real-time and historical air quality measurements.

• Air Quality Index (AQI) and particulate matter 2.5 (PM2.5) concentrations were the exposure variables examined.
• Data was collected for three days preceding each patient's stroke onset.
• Data was analysed using SPSS version 27.
• The study used a bidirectional cohort design to explore the association between stroke type and air quality exposure variables.