Elizabeth A Shephard

Clinical features of bladder cancer in primary care

BACKGROUND Bladder cancer accounts for over 150,000 deaths worldwide. No screening is available, so diagnosis depends on investigations of symptoms. Of these, only visible haematuria has been studied in primary care. AIM To identify and quantify the features of bladder cancer in primary care. DESIGN AND SETTING Case-control study, using electronic medical records from UK primary care. METHOD Participants were 4915 patients aged ≥40 years, diagnosed with bladder cancer January 2000 to December 2009, and 21,718 age, sex, and practice-matched controls, were selected from the General Practice Research Database, UK. All clinical features independently associated with bladder cancer using conditional logistic regression were identified, and their positive predictive values for bladder cancer, singly and in combination, were estimated. RESULTS Cases consulted their GP more frequently than controls before diagnosis: median 15 consultations (interquartile range 9-22) versus 8 (4-15): P<0.001. Seven features were independently associated with bladder cancer: visible haematuria, odds ratio 34 (95% confidence interval [CI] = 29 to 41), dysuria 4.1 (95% CI = 3.4 to 5.0), urinary tract infection 2.2 (95% CI = 2.0 to 2.5), raised white blood cell count 2.1 (95% CI = 1.6 to 2.8), abdominal pain 2.0 (95% CI = 1.6 to 2.4), constipation 1.5 (95% CI = 1.2 to 1.9), raised inflammatory markers 1.5 (95% CI = 1.2 to 1.9), and raised creatinine 1.3 (95% CI = 1.2 to 1.4). The positive predictive value for visible haematuria in patients aged ≥60 years was PPV of 2.6% (95% CI = 2.2 to 3.2). CONCLUSION Visible haematuria is the commonest and most powerful predictor of bladder cancer in primary care, and warrants investigation. Most other previously reported features of bladder cancer were associated with the disease, but with low predictive values. There is a need for improved diagnostic methods, for those patients whose bladder cancer presents without visible haematuria.

The use of electronic databases in primary care research

DISCOVERY Research Group, Peninsula College of Medicine & Dentistry, Veysey Building, Salmon Pool Lane, Exeter, EX2 4SG, UK and Doctoral student, School of Social & Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol, BS8 2PS, UK. *Correspondence to W Hamilton Peninsula College of Medicine & Dentistry, Veysey Building, Salmon Pool Lane, Exeter, EX2 4SG, UK; E-mail: willie.hamilton@pcmd.ac.uk Received 31 May 2011; Accepted 6 June 2011.

Clinical features of kidney cancer in primary care: a case-control study using primary care records

BACKGROUND Kidney cancer accounts for over 4000 UK deaths annually, and is one of the cancer sites with a poor mortality record compared with Europe. AIM To identify and quantify all clinical features of kidney cancer in primary care. DESIGN Case-control study, using General Practice Research Database records. METHOD A total of 3149 patients aged ≥40 years, diagnosed with kidney cancer between 2000 and 2009, and 14 091 age, sex and practice-matched controls, were selected. Clinical features associated with kidney cancer were identified, and analysed using conditional logistic regression. Positive predictive values for features of kidney cancer were estimated. RESULTS Cases consulted more frequently than controls in the year before diagnosis: median 16 consultations (interquartile range 10-25) versus 8 (4-15): P<0.001. Fifteen features were independently associated with kidney cancer: visible haematuria, odds ratio 37 (95% confidence interval [CI] = 28 to 49), abdominal pain 2.8 (95% CI = 2.4 to 3.4), microcytosis 2.6 (95% CI = 1.9 to 3.4), raised inflammatory markers 2.4 (95% CI = 2.1 to 2.8), thrombocytosis 2.2 (95% CI = 1.7 to 2.7), low haemoglobin 1.9 (95% CI = 1.6 to 2.2), urinary tract infection 1.8 (95% CI = 1.5 to 2.1), nausea 1.8 (95% CI = 1.4 to 2.3), raised creatinine 1.7 (95% CI = 1.5 to 2.0), leukocytosis 1.5 (95% CI = 1.2 to 1.9), fatigue 1.5 (95% CI = 1.2 to 1.9), constipation 1.4 (95% CI = 1.1 to 1.7), back pain 1.4 (95% CI = 1.2 to 1.7), abnormal liver function 1.3 (95% CI = 1.2 to 1.5), and raised blood sugar 1.2 (95% CI = 1.1 to 1.4). The positive predictive value for visible haematuria in patients aged ≥60 years was 1.0% (95% CI = 0.8 to 1.3). CONCLUSION Visible haematuria is the commonest and most powerful single predictor of kidney cancer, and the risk rises when additional symptoms are present. When considered alongside the risk of bladder cancer, the overall risk of urinary tract cancer from haematuria warrants referral.

Quantifying the risk of multiple myeloma from symptoms reported in primary care patients: a large case-control study using electronic records

BACKGROUND Patients with myeloma experience the longest diagnostic delays compared with patients with other cancers in the UK; 37% are diagnosed through emergency presentations. AIM To identify and quantify the risk of myeloma from specific clinical features reported by primary care patients. DESIGN AND SETTING Matched case-control study using General Practice Research Database primary care electronic records. METHOD Putative clinical features of myeloma were identified and analysed using conditional logistic regression. Positive predictive values (PPVs) were calculated for the consulting population. RESULTS A total of 2703 patients aged ≥40 years, diagnosed with myeloma between 2000 and 2009, and 12 157 age, sex, and general practice-matched controls were identified. Sixteen features were independently associated with myeloma: hypercalcaemia, odds ratio 11.4 (95% confidence interval [CI] = 7.1 to 18), cytopenia 5.4 (95% CI = 4.6 to 6.4), raised inflammatory markers 4.9 (95% CI = 4.2 to 5.8), fracture 3.1 (95% CI = 2.3 to 4.2), raised mean corpuscular volume 3.1 (95% CI = 2.4 to 4.1), weight loss 3.0 (95% CI = 2.0 to 4.5), nosebleeds 3.0 (95% CI = 1.9 to 4.7), rib pain 2.5 (95% CI = 1.5 to 4.4), back pain 2.2 (95% CI = 2.0 to 2.4), other bone pain 2.1 (95% CI = 1.4 to 3.1), raised creatinine 1.8 (95% CI = 1.5 to 2.2), chest pain 1.6 (95% CI = 1.4 to 1.8), joint pain 1.6 (95% CI = 1.2 to 2.2), nausea 1.5 (95% CI = 1.1 to 2.1), chest infection 1.4 (95% CI = 1.2 to 1.6), and shortness of breath 1.3 (95% CI = 1.1 to 1.5). Individual symptom PPVs were generally <1%, although were >10% for some symptoms when combined with leucopenia or hypercalcaemia. CONCLUSION Individual symptoms of myeloma in primary care are generally low risk, probably explaining diagnostic delays. Once simple primary care blood tests are taken, risk estimates change. Hypercalcaemia and leucopenia are particularly important abnormalities, and coupled with symptoms, strongly suggest myeloma.

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

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.

Is omission of free text records a possible source of data loss and bias in Clinical Practice Research Datalink studies? A case–control study

Objectives To estimate data loss and bias in studies of Clinical Practice Research Datalink (CPRD) data that restrict analyses to Read codes, omitting anything recorded as text. Design Matched case–control study. Setting Patients contributing data to the CPRD. Participants 4915 bladder and 3635 pancreatic, cancer cases diagnosed between 1 January 2000 and 31 December 2009, matched on age, sex and general practitioner practice to up to 5 controls (bladder: n=21 718; pancreas: n=16 459). The analysis period was the year before cancer diagnosis. Primary and secondary outcome measures Frequency of haematuria, jaundice and abdominal pain, grouped by recording style: Read code or text-only (ie, hidden text). The association between recording style and case–control status (χ2 test). For each feature, the odds ratio (OR; conditional logistic regression) and positive predictive value (PPV; Bayes’ theorem) for cancer, before and after addition of hidden text records. Results Of the 20 958 total records of the features, 7951 (38%) were recorded in hidden text. Hidden text recording was more strongly associated with controls than with cases for haematuria (140/336=42% vs 556/3147=18%) in bladder cancer (χ2 test, p<0.001), and for jaundice (21/31=67% vs 463/1565=30%, p<0.0001) and abdominal pain (323/1126=29% vs 397/1789=22%, p<0.001) in pancreatic cancer. Adding hidden text records corrected PPVs of haematuria for bladder cancer from 4.0% (95% CI 3.5% to 4.6%) to 2.9% (2.6% to 3.2%), and of jaundice for pancreatic cancer from 12.8% (7.3% to 21.6%) to 6.3% (4.5% to 8.7%). Adding hidden text records did not alter the PPV of abdominal pain for bladder (codes: 0.14%, 0.13% to 0.16% vs codes plus hidden text: 0.14%, 0.13% to 0.15%) or pancreatic (0.23%, 0.21% to 0.25% vs 0.21%, 0.20% to 0.22%) cancer. Conclusions Omission of text records from CPRD studies introduces bias that inflates outcome measures for recognised alarm symptoms. This potentially reinforces clinicians’ views of the known importance of these symptoms, marginalising the significance of ‘low-risk but not no-risk’ symptoms.

Clinical relevance of thrombocytosis in primary care: a prospective cohort study of cancer incidence using English electronic medical records and cancer registry data

Background Thrombocytosis (raised platelet count) is an emerging risk marker of cancer, but the association has not been fully explored in a primary care context. Aim To examine the incidence of cancer in a cohort of patients with thrombocytosis, to determine how clinically useful this risk marker could be in predicting an underlying malignancy. Design and setting A prospective cohort study using Clinical Practice Research Datalink data from 2000 to 2013. Method The 1-year incidence of cancer was compared between two cohorts: 40 000 patients aged ≥40 years with a platelet count of >400 × 109/L (thrombocytosis) and 10 000 matched patients with a normal platelet count. Sub-analyses examined the risk with change in platelet count, sex, age, and different cancer sites. Results A total of 1098 out of 9435 males with thrombocytosis were diagnosed with cancer (11.6%; 95% confidence interval [CI] = 11.0 to 12.3), compared with 106 of 2599 males without thrombocytosis (4.1%; 95% CI = 3.4 to 4.9). A total of 1355 out of 21 826 females with thrombocytosis developed cancer (6.2%; 95% CI = 5.9 to 6.5), compared with 119 of 5370 females without (2.2%; 95% CI = 1.8 to 2.6). The risk of cancer increased to 18.1% (95% CI = 15.9 to 20.5) for males and 10.1% (95% CI = 9.0 to 11.3) for females, when a second raised platelet count was recorded within 6 months. Lung and colorectal cancer were more commonly diagnosed with thrombocytosis. One-third of patients with thrombocytosis and lung or colorectal cancer had no other symptoms indicative of malignancy. Conclusion Thrombocytosis is a risk marker of cancer in adults; 11.6% and 6.2% cancer incidence in males and females, respectively, is worthy of further investigation for underlying malignancy. These figures well exceed the National Institute for Health and Care Excellence-mandated risk threshold of 3% risk to warrant referral for suspected cancer.

How useful is thrombocytosis in predicting an underlying cancer in primary care? a systematic review

Background. Although the association between raised platelet count (thrombocytosis) and cancer has been reported in primary and secondary care studies, UK GPs are unaware of it, and it is insufficiently evidenced for laboratories to identify and warn of it. This systematic review aimed to identify and collate evidence from studies that have investigated thrombocytosis as an early marker of cancer in primary care. Methods. EMBASE (OvidSP), Medline (Ovid), Web of Science and The Cochrane Library were searched for relevant studies. Eligible studies had reported estimates of the association between thrombocytosis and cancer, in adults aged ≥40 in a primary care setting. Raw data from included studies were used to calculate positive predictive values and likelihood ratios (LRs) for cancer. Results. Nine case–control studies were identified. Study quality was judged to be high. Included studies reported on the following cancer sites: colorectal, lung, ovary, bladder, kidney, pancreas, oesophago-gastric, uterus and breast. LRs indicated that thrombocytosis was a predictor of cancer in all sites except breast. In a consulting population, thrombocytosis is most highly predictive of lung and colorectal cancer. Conclusions. These results suggest that patients with thrombocytosis in primary care have an increased risk of cancer, and that some, but not all, cancers have raised platelets as an early marker. This finding is expected to be of use in primary care, for GPs receiving blood test results unexpectedly showing high platelet counts. Further research is needed to identify the cancers that are most strongly associated with thrombocytosis.

Symptoms of adult chronic and acute leukaemia before diagnosis: large primary care case-control studies using electronic records

BACKGROUND Leukaemia is the eleventh commonest UK cancer. The four main subtypes have different clinical profiles, particularly between chronic and acute types. AIM To identify the symptom profiles of chronic and acute leukaemia in adults in primary care. DESIGN AND SETTING Matched case-control studies using Clinical Practice Research Datalink records. METHOD Putative symptoms of leukaemia were identified in the year before diagnosis. Conditional logistic regression was used for analysis, and positive predictive values (PPVs) were calculated to estimate risk. RESULTS Of cases diagnosed between 2000 and 2009, 4655 were aged ≥40 years (2877 chronic leukaemia (CL), 937 acute leukaemia (AL), 841 unreported subtype). Ten symptoms were independently associated with CL, the three strongest being: lymphadenopathy (odds ratio [OR] 22, 95% confidence interval [CI] = 13 to 36), weight loss (OR 3.0, 95% CI = 2.1 to 4.2), and bruising (OR 2.3, 95% CI = 1.6 to 3.2). Thirteen symptoms were independently associated with AL, the three strongest being: nosebleeds and/or bleeding gums (OR 5.7, 95% CI = 3.1 to 10), fever (OR 5.3, 95% CI = 2.7 to 10), and fatigue (OR 4.4, 95% CI = 3.3 to 6.0). No individual symptom or combination of symptoms had a PPV >1%. CONCLUSION The symptom profiles of CL and AL have both overlapping and distinct features. This presents a dichotomy for GPs: diagnosis, by performing a full blood count, is easy; however, the symptoms of leukaemia are non-specific and of relatively low risk. This explains why many leukaemia diagnoses are unexpected findings.

Early detection of multiple myeloma in primary care using blood tests: a case–control study in primary care

Background Multiple myeloma is a haematological cancer characterised by numerous non-specific symptoms leading to diagnostic delay in a large proportion of patients. Aim To identify which blood tests are useful in suggesting or excluding a diagnosis of myeloma. Design and setting A matched case–control study set in UK primary care using routinely collected data from the Clinical Practice Research Datalink. Method Symptom prevalence and blood tests were analysed up to 5 years before diagnosis in 2703 cases and 12 157 matched controls. Likelihood ratios (LR) were used to classify tests or their combinations as useful rule-in tests (LR+ = ≥5), or rule-out tests (LR− = ≤0.2). Results Raised plasma viscosity (PV) had an LR+ = 2.0, 95% confidence interval [CI] = 1.7 to 2.3; erythrocyte sedimentation rate (ESR) 1.9, 95% CI = 1.7 to 2.0; and C-reactive protein (CRP) 1.2, 95% CI = 1.1 to 1.4. A normal haemoglobin had an LR− = 0.42, 95% CI = 0.39 to 0.45; calcium LR− = 0.81, 95% CI = 0.78 to 0.83; and creatinine LR− = 0.80, 95% CI = 0.77 to 0.83. The test combination with the lowest LR− was all normal haemoglobin with calcium and PV, which had an LR− = 0.06, 95% CI = 0.02 to 0.18, though the LR− for normal haemoglobin and PV together was 0.12 (95% CI = 0.07 to 0.23). Conclusion Plasma viscosity and ESR are better for both ruling in and ruling out the disease compared with C-reactive protein. A combination of a normal ESR or PV and normal haemoglobin is a simple rule-out approach for patients currently being tested in primary care.