These data show that the hypercoagulable state in PCOS can be completely accounted for by BMI and its associated inflammation, and enhanced insulin resistance. In comparison to the normal controls, overall 10 pro-coagulation proteins were elevated in PCOS; plasminogen activator inhibitor–1 (PAI–1), fibrinogen, fibrinogen gamma chain, fibronectin, von Willebrand factor, D-dimer, P-selectin, plasma kallikrein. anticoagulant vitamin K-dependent protein S and heparin cofactor II, whilst prothrombin was decreased. These results are in accord with others who have reported changes in coagulation proteins in PCOS (4, 13), but underlying pathophysiology has not been previously described and shows that in PCOS alterations in the coagulation factors appears complex and multifactorial. When normal weight (BMI≤25) PCOS patients were compared with normal weight control subjects, insulin resistance remained elevated and heparin cofactor 2, that is protective and inactivates thrombin in tissues, differed. These data are in accord with the association of heparin cofactor 2 with insulin resistance (14), indicating that normal weight PCOS subjects likely have no additional risk associated with a hypercoagulable state; however, obesity with associated inflammation markedly exaggerates the hypercoagulable state with an increased number of clotting parameters altered. The multivariate analysis showed that all of the changes in the coagulation proteins could be accounted for by BMI, inflammation and insulin resistance.
It is well recognized that obesity causes inflammation and increased insulin resistance (15, 16) and is associated with changes in coagulation parameters. For example, fibronectin is correlated to BMI (17) and obesity is associated with increased PAI–1 in PCOS (18). Others have reported, using a repeated fibrin formation and degradation functional assay, that “overall hemostatic potential” was BMI-dependent and not associated with PCOS (19). Central fat mass has been associated with fibrinogen, CRP, coagulation factor XIII, waist-to-hip ratio, plasminogen, PAI–1, plasmin inhibitor, and thrombin activatable fibrinolysis inhibitor (20)
Conversely, thrombin-activatable fibrinolysis inhibitor, PAI–1, D-dimer, Antithrombin III and thrombomodulin were reported to be significantly increased in women with PCOS compared with age- and BMI-matched controls, suggesting that alterations in these proteins are BMI-independent and due to other factors such as inflammation and insulin resistance, as reported here (4).
Inflammation (CRP) correlated significantly with antithrombin III, heparin cofactor 2, fibrinogen gamma chain, D-dimer, P-selectin, fibronectin, and its fragments 3 and 4, vitamin K dependent protein S, alpha 2 antiplasmin and fibrinogen. Inflammation crosstalk with coagulation leading to increased coagulopathy is well recognized; however, with the initiation of coagulation, the coagulation proteases may then modulate the inflammatory response (21, 22). In PCOS, both CRP and fibrinogen are predicted by BMI in accord with obesity initiating the increased inflammation (23) and particularly CRP, PAI–1, D-dimer, Antithrombin III with central fat mass as noted above (20).
In this study, insulin resistance (HOMA-IR) correlated with Antithrombin III, heparin cofactor 2, P-selectin, fibronectin, vitamin K dependent protein S and alpha 2 antiplasmin. It is recognized that insulin resistance is associated with enhanced thrombogenesis (24); however, it is difficult to determine the contribution of insulin resistance alone to its association with obesity and inflammation metabolic syndrome lipid parameters (25–27).
As noted above, there are reports of changes in coagulation proteins in PCOS (4, 13) and changes in functional assays (2, 3); however, conversely others have not found changes in the coagulation proteins between PCOS and controls (28). It can be seen from the data presented here that the likely reason for these discrepancies are due to the patient population being studied with the results dependent on the degree of obesity, inflammation and insulin resistance present. In addition, the PCOS phenotype may have an important role, with those having all three of the diagnostic criteria exhibiting the metabolic phenotype with increased insulin resistance in comparison to those with only two of the three diagnostic criteria (29)
The hypercoagulation state is in homeostasis with the pro-coagulation protein changes seen here in PCOS being balanced by the reduction in prothrombin and increased vitamin K-dependent protein S and heparin cofactor II that we also report; however, COVID–19 disease may shift this balance towards a hyper-procoagulant state. Patients infected with COVID–19 with acute respiratory distress syndrome (ARDS) show a procoagulant pattern of coagulation markers and elevation of fibrinogen and fibrin degradation products (D-dimers) which could drive organ failure and death (8).
Limitations of this study include that it was a cross sectional study but this was mitigated by the large number of subjects. In addition, only the proteins involved in the coagulation pathways were measured and no functional assays were undertaken in this study.
In conclusion, thehypercoagulable state in PCOS can be fully accounted for by BMI, inflammation and insulin resistance, suggesting that only obese PCOS women would be predisposed to an enhanced risk for severe COVID–19-related disease.