Seasonal Differences in Mortality, Comorbidities, and Hospital Admissions Outcomes Among Elderly Cancer Patients with Venous Thromboembolism
Authors: Mirchandani Mohit , Ravinath Naik Anagha , Kanagala Sai Gautham , Asfeen Ummul , Reddy Shilpa , Rajarajan Srinishant , Gadhiya Dhruvkumar , Babu Kalaivani , Desai Rupak 
Published: December 2024

Background: Increasing global temperatures significantly impact vulnerable populations, especially elderly cancer patients. Heat waves worsen cardiovascular and respiratory diseases, raising morbidity and mortality rates. Seasonal variations in health outcomes may lead to spikes in hospitalizations during extreme weather, likely due to altered environmental factors, pathophysiological mechanisms, and drug pharmacokinetics. These changes can exacerbate underlying comorbidities, leading to more hospitalizations. To our knowledge, this is the first study to investigate whether comorbidities show seasonal variation in cancer hospitalizations among the elderly with Venous Thromboembolism(VTE), potentially necessitating more precise healthcare strategies.

Methods: Elderly (≥65 years) cancer hospitalizations with VTE from the National Inpatient Sample (NIS) 2016-2020 (ICD-10) were categorized into summer and non-summer months. Demographics, clinical profiles, MACCE, all-cause mortality (ACM), hyperlipidemia, Peripheral vascular disease(PVD), and Hypertension(HTN) were compared. Chi-square tests analyzed comorbidities, while multivariable regression controlled for covariates to assess ACM risk. Mann-Whitney U tests compared length of stay (LOS) and hospital costs between seasons.

Results: A total of 251,840 hospitalizations for elderly cancer patients with VTE were identified, with 75.5% occurring during non-summer months and 24.5% during summer months. ACM was higher during non-summer months compared to summer months (10.9% vs. 10.5%, p &lt;0.009). MACCE rates were statistically insignificant between seasons (9.5% vs. 9.5%, p = 0.604).

From 2016 to 2020, there was a statistically significant increase in all-cause mortality (ACM) during both non-summer (10.6% &gt; 10.8% &gt; 11.1% &gt; 10.5% &gt; 11.5%; Ptrend=0.003) and summer months (10.0% &gt; 9.5% &gt; 10.4% &gt; 10.8% &gt; 11.8%; Ptrend&lt;0.001). Both ACM and MACCE showed an upward trend since 2016, during summer (7.5% &gt; 8.8% &gt; 9% &gt; 9.7% &gt; 12.1%) and non-summer months (7.3% &gt; 8.9% &gt; 9.8% &gt; 9.9% &gt; 11.1%) (Ptrend &lt; 0.001).

Significant differences were observed in hospitalizations with underlying comorbidities: PVD (9.6% non-summer vs. 8.7% summer, p &lt; 0.001), hyperlipidemia (42.3% non-summer vs. 41.5% summer, p &lt; 0.001), and prior chemotherapy (10.4% non-summer vs. 10.1% summer, p = 0.043). The most prevalent comorbidities among total admissions for hospitalizations with VTE were hyperlipidemia (41.7%) and hypertension (42.9%), with most admissions covered by Medicare beneficiaries (88.2%).

The median LOS was 5 days for both summer and non-summer months. Mann-Whitney U tests showed significant differences in LOS and hospital costs (both p &lt; 0.001), but not in age at admission (p = 0.161). Multivariable regression showed no significant difference in the odds of mortality between summer and non-summer months (OR: 0.96; 95% CI: 0.89-1.02).

Conclusion: Our study concludes that there is no significant difference in mortality rates between summer and non-summer months. However, comorbidities such as PVD and hyperlipidaemia did increase hospitalizations, suggesting a need for targeted interventions. Limitations include potential misclassification risk with a focus on Medicare beneficiaries, limiting generalizability to younger patients. Further studies are needed to validate these findings and develop effective intervention strategies.