Key points Ask What is the risk of hematologic malignancy and the diagnostic utility of serum lactate dehydrogenase testing among patients with undifferentiated pruritus? Findings In this cohort study of 327,502 patients and 327,502 matched controls, patients with undifferentiated pruritus had an increased risk of being diagnosed with a hematological malignancy in the first year, and serum lactate dehydrogenase level was not associated with an increased risk. of hematological cancer. Meaning Clinicians should consider a thorough review of symptoms and evaluation of cancer risk factors when deciding whether to work up patients presenting with undifferentiated pruritus. |
Importance
Although pruritus is common in patients with hematologic cancers, it is unknown whether patients with undifferentiated pruritus are at increased risk of developing hematologic cancer. Furthermore, it is unclear whether the serum lactate dehydrogenase (LDH) level, commonly requested for cancer screening, has diagnostic utility in patients with pruritus.
Aim
To evaluate the risk of hematological cancer and the diagnostic utility of LDH level in patients with undifferentiated pruritus.
Design, environment and participants
This population-level retrospective cohort analysis was performed using TriNetX Research Network, a global health record database covering more than 69 million patients, from 2002 to 2020.
The study included 327,502 eligible patients diagnosed with pruritus not otherwise specified, excluding those with existing chronic pruritic dermatoses or systemic diseases known to cause pruritus, along with 327,502 matched controls.
Exhibitions
Development of hematological cancer within 1 year, 5 years and 10 years after diagnosis of pruritus not otherwise specified.
Main results and measures
The primary outcomes of the study were 1-year, 5-year, and 10-year relative risks (RRs) for the development of 9 hematologic malignancies in patients with pruritus compared with control patients.
Secondary outcomes were 1-year, 5-year, and 10-year RRs for any hematologic malignancy at different LDH cutoff points (250 U/L and 500 U/L).
Results
After matching, the pruritus and control cohorts each had 327,502 patients (68.1% female patients; 0.4% American Indian or Alaska Native patients; 3.5% Asian patients; 22.2% Black patients ; 0.1% Native Hawaiian or Pacific Islander patients; 59.3% White patients; mean [SD] age, 42.2 [22] years).
Patients with pruritus had an increased 1-year risk of Hodgkin lymphoma (RR, 4.42; 95% CI, 2.83-6.88), myeloid leukemia (RR, 2.56; 95% CI, 1. 79-3.67), multiple myeloma (RR, 2.38; 95% CI, 1.66-3.41), non-Hodgkin lymphoma (RR, 2.35; 95% CI, 1.96-2.82 ), monoclonal gammopathy (RR, 1.90; 95% CI, 1.55-2.32), myelodysplastic syndrome (RR, 1.74; 95% CI, 1.14-2.64), and lymphocytic leukemia (RR , 1.47; 95% CI, 1.07-2.02).
After 12 months, cancer risk was comparable to controls. Patients with pruritus had elevated LDH levels.
Conclusions and relevance
In this cohort study, the RR of hematological cancer in patients with undifferentiated pruritus was highest in the first 12 months and the LDH level had limited diagnostic utility in these patients.
Clinicians should consider a thorough review of symptoms and evaluation of cancer risk factors when deciding whether to work up patients presenting with undifferentiated pruritus.
Although patients with undifferentiated pruritus had higher serum LDH levels, these levels were not associated with an increased risk of hematologic cancer.
“Future studies should examine covariates, such as age or patient-specific risk factors, for the development of specific hematologic cancers in patients with pruritus, as well as optimal diagnostic and prognostic hematologic workup,” the team wrote.
