Quantifying the risk of Hodgkin lymphoma in symptomatic primary care patients aged ≥40 years: a case–control study using electronic records

Background In the UK, approximately five people are diagnosed with Hodgkin lymphoma (HL) daily. One-tenth of diagnoses are in those aged >75 years. Aim To establish a symptom profile of HL and quantify their risk in primary care patients aged ≥40 years. Design and setting Matched case–control study using Clinical Practice Research Datalink patient records. Method Putative clinical features of HL were identified in the year before diagnosis. Results were analysed using conditional logistic regression and positive predictive values (PPVs) calculated for the consulting population. Results Two-hundred and eighty-three patients aged ≥40 years, diagnosed with HL between 2000 and 2009, and 1237 age, sex, and general practice-matched participants were studied. Six features were independently associated with HL: lymphadenopathy (OR 280, 95% confidence interval [CI] = 25 to 3100), head and neck mass not described as lymphadenopathy (OR 260, 95% CI = 21 to 3200), other mass (OR 12, 95% CI = 4.4 to 35), thrombocytosis (OR 6.0, 95% CI = 2.6 to 14), raised inflammatory markers (OR 5.2, 95% CI = 3.0 to 9.0), and low full blood count (OR 2.8, 95% CI = 1.6 to 4.8). Lymphadenopathy per se has a positive predictive value (PPV) of 5.6% for HL in patients aged ≥60 years. Conclusion Consistent with secondary care findings, lymphadenopathy is the clinical feature with the highest risk of HL in primary care and warrants urgent investigation.