A Retrospective Review of Diagnoses Coexisting with a Positive Lupus Anticoagulant In a Community Hospital

Lupus anticoagulant (AC) is an immunoglobulin which prolongs in vitro phospholipid coagulation tests. Although activated partial thromboplastin time is prolonged, only rarely is it associated with a bleeding tendency. It is, however, associated with arterial and venous thromboembolism (VTE) as well as fetal miscarriages. Due to the transient nature of antibodies, a true positive lupus AC requires confirmation at least 12 weeks from the initial test.

We performed a single-center, retrospective chart review of patients who tested positive for lupus AC at Lenox Hill Hospital between January 2003 and December 2007. Admitted patients who tested positive by the dilute Russell's viper venom time (dRVVT) or the hexagonal phase test during this four year interval were included in the study. Medical records were reviewed for: age, gender, admitting/discharge diagnoses, secondary diagnoses, presence or history of VTE, and history of pregnancy loss. The aim of the study was to determine 1) patients with positive lupus AC tests and their admitting/discharge diagnoses, 2) VTE prevalence among patients with a positive lupus AC test, 3) new and previously diagnosed malignancies in those patients with a positive lupus AC test, and 4) the prevalence of loss of pregnancy among female patients with a positive lupus AC.

A total of 391 patients tested positive for lupus AC during the 4-year period. Of these, 59 were outpatient tests and excluded from our analyses. Our sample was the remaining 332 hospitalized patients. Of these, 142 (42.8%) patients had a positive hexagonal phase test, 41 (12.3%) distinct cases had a positive dRVVT, and the remaining 149 cases (44.9%) were positive for both. The mean age of the sample was 66.3 years old, ranging from 21 to 99. Notably, 181 patients were male and 151 were female.

The highest prevalence of lupus AC was associated with the following admitting/discharge diagnostic categories: cardiovascular, 31.9%, infectious disease, 14.5%, VTE, 9.3%, and hematology, 5.7%. Of our sample, 18 patients had a prior history of a VTE and 79 patients were diagnosed with a new event during the admission. Of those 18 patients, 13 (72.2%) were diagnosed with a new VTE on the reviewed hospitalization.

From our sample, there were 69 malignant diagnoses, either new or by history. High prevalence malignancies were prostate cancer (20.3%), lung cancer (14.5%), colon cancer (8.7%), and non-Hodgkin's lymphoma (11.6%). Remarkably, only one (0.66%) of the female patients in our sample had a history of miscarriage.

In the spectrum of antiphospholipid syndrome, lupus AC is clinically significant due to its association with thromboembolic events. In our study, the highest prevalence of a lupus AC was seen in the cardiovascular, infectious disease, and VTE diagnostic categories. Confounding factors included our institution's high cardiovascular and infectious disease admission rates, core measures implemented by our hospital (i.e. acute myocardial infarction, congestive heart failure, and pneumonia), and the advanced mean age of our patients, > 50 years old.

From our sample, 23.8% were diagnosed with new VTEs. Those with a history of VTE demonstrated an increased susceptibility to developing a new VTE. This may be due to superimposing factors such as prolonged immobilization and invasive procedures during hospitalization on an already existing hypercoaguable state.

Prostate cancer was the highest prevalence malignancy found in this male predominant, high mean age sample. Though malignancy itself is a hypercoaguable state, of the 69 malignant diagnoses, only 4 acute VTEs were diagnosed. Therefore, malignancy and lupus AC may not have an additive thromboembolic effect.

Limitations of this study include lack of a confirmatory lupus AC test performed 12 weeks from the initial positive test, a large overlap among concomitant secondary diagnoses which may affect the prevalence of a lupus AC in each diagnostic category, and an insufficient gestational history in patients' charts. Insufficient histories can result in under observation of miscarriages in the setting of lupus AC.

In this retrospective review of 332 patients with lupus AC, we concluded that hospitalized patients with lupus AC had an increased likelihood of developing a VTE. Additionally, the hypercoaguable state of malignancy may not have an additive thrombotic effect in patients with lupus AC.

No relevant conflicts of interest to declare.