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

Abstract

BACKGROUND: Non-Hodgkin lymphoma (NHL) is the sixth most common cancer in the UK; approximately 35 people are diagnosed and 13 die from the disease daily. AIM: To identify the primary care clinical features of NHL and quantify their risk in symptomatic patients. DESIGN AND SETTING: Matched case-control study using Clinical Practice Research Datalink patient records. METHOD: Putative clinical features of NHL were identified in the year before diagnosis. Results were analysed using conditional logistic regression and positive predictive values (PPVs). RESULTS: A total of 4362 patients aged ≥40 years, diagnosed with NHL between 2000 and 2009, and 19 468 age, sex, and general practice-matched controls were studied. Twenty features were independently associated with NHL. The five highest risk symptoms were lymphadenopathy, odds ratio (OR) 263 (95% CI = 133 to 519), head and neck mass not described as lymphadenopathy OR 49 (95% CI = 32 to 74), other mass OR 12 (95% CI = 10 to 16), weight loss OR 3.2 (95% CI = 2.3 to 4.4), and abdominal pain OR 2.5 (95% CI = 2.1 to 2.9). Lymphadenopathy has a PPV of 13% for NHL in patients ≥60 years. Weight loss in conjunction with repeated back pain or raised gamma globulin had PPVs >2%. CONCLUSION: Unexplained lymphadenopathy in patients aged ≥60 years produces a very high risk of NHL in primary care. These patients warrant urgent investigation, potentially sooner than 6 weeks from initial presentation where the GP is particularly concerned.