You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

BACKGROUND: Limited existing data suggest the novel coronavirus disease 2019 (Covid-19) may increase risk for venous thromboembolism (VTE) but information from large, ethnically diverse populations with appropriate controls are lacking. RESEARCH QUESTION: Does the rate of VTE among adults hospitalized with Covid-19 differ from matched hospitalized controls without Covid-19? STUDY DESIGN AND METHODS: We conducted a retrospective study among hospitalized adults with laboratory-confirmed Covid-19 and hospitalized adults without evidence of Covid-19 matched on age, gender, race/ethnicity, acute illness severity, and month of hospitalization between February-August 2020 from two integrated healthcare delivery systems with 36 hospitals. Outcomes included VTE (deep venous thrombosis or pulmonary embolism ascertained using diagnosis codes combined with validated natural language processing algorithms applied to electronic health records) and death from any cause at 30 days. Fine and Gray hazards regression was performed to evaluate the association of Covid-19 with VTE after accounting for competing risk of death and residual differences between groups, as well as identifying predictors of VTE in patients with Covid-19. RESULTS: We identified 6,319 adults with Covid-19 and 6,319 matched adults without Covid-19, with mean (SD) age of 60.0 (17.2) years, 46% women, 53.1% Hispanic, 14.6% Asian/Pacific Islander and 10.3% Black. During 30-day follow-up, 313 validated VTE (160 Covid-19, 153 controls) and 1172 deaths (817 Covid-19, 355 controls) occurred. Adults with Covid-19 had a more than threefold adjusted risk of VTE (adjusted hazard ratio 3.48, 95% Confidence Interval 2.03-5.98) compared with matched controls. Predictors of VTE in Covid-19 patients included age >/=55 years, Black race, prior VTE, diagnosed sepsis, prior moderate or severe liver disease, body mass index >/=40 kg/m(2), and platelet count >217 k/mcL. INTERPRETATION: Among ethnically diverse hospitalized adults, Covid-19 infection increased the risk of VTE, and selected patient characteristics were associated with higher thromboembolic risk in the setting of Covid-19.
["Diagnosis", "Treatment"]