Decline in Cancer Diagnoses during the 'Zero COVID' Policy in Hong Kong: Indirect Spillover Impact of the COVID-19 Pandemic

AIMS

Despite a largely successful 'zero COVID' policy in 2020, the COVID-19 pandemic disrupted routine cancer services in the city of Hong Kong. The aims of this study were to examine the trends in cancer incidence before and during the COVID-19 pandemic and estimate missed cancer diagnoses.

MATERIALS AND METHODS

We used population-based data from the Hong Kong Cancer Registry 1983-2020 to examine the trends of age- and sex-standardised cancer incidence before and during the COVID-19 pandemic. We applied: (i) the annual average percentage change (AAPC) calculated using the Joinpoint regression model and (ii) the autoregressive integrated moving average (ARIMA) model to forecast cancer incidence rates in 2020. Missed cancer diagnoses in 2020 were estimated by comparing forecasted incidence rates to reported rates. A subgroup analysis was conducted by sex, age and cancer site.

RESULTS

The cancer incidence in Hong Kong declined by 4.4% from 2019 to 2020 (male 8.1%; female 1.1%) compared with the long-term AAPC of 0.5% from 2005 to 2019 (95% confidence interval 0.3, 0.7). The gap between the reported and forecasted incidence for 2020 ranged from 5.1 to 5.7% (male 8.5%, 9.8%; female 2.3%, 3.5%). We estimated 1525-1596 missed cancer diagnoses (ARIMA estimate -98, 3148; AAPC 514, 1729) in 2020. Most missed diagnoses were in males (ARIMA 1361 [327, 2394]; AAPC 1401 [1353, 1460]), with an estimated 479-557 missed cases of colorectal cancer (ARIMA 112, 837; AAPC 518, 597) and 256-352 missed cases of prostate cancer (AAPC 231, 280; ARIMA 110, 594).

CONCLUSION

The incidence of new cancer diagnoses declined in 2020 contrary to the long-term increase over the previous decades. Significantly lower diagnoses than expected were observed in males, particularly for colorectal and prostate cancers. Fewer reported cancer cases indicate missed diagnoses and could lead to delayed treatment that could impact future health outcomes.

Malaysian consensus statement on FDG PET-CT reporting format for lymphoma

Over the past decade, 18F-Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PETCT) has emerged as an important imaging modality in the management of lymphoma. Since the introduction of Deauville scoring system (2009) and the Lymphoma Response Assessment Criteria (2014), clinicians are now sharing a common language in the management of lymphoma. In Malaysia, nearly a third of PET-CT request is related to lymphoma imaging. Though there are extensive publications regarding these scoring systems and assessment criteria for lymphoma, there are hardly any literature on the reporting format for the 18F-FDG PET-CT in this disease. The variable reporting formats have on many occasions caused confusion not only to the referring clinicians but also to nuclear medicine physicians. Thus, a working committee comprising experienced nuclear medicine physicians and haematologists in Malaysia have agreed and made a joint recommendation on the standard reporting format for 18F-FDG PET-CT in Lymphoma. This recommendation will minimize inter-observer discrepancies in reporting, facilitate the understanding of the report of the referring clinicians as well as facilitate counseling between patients and clinicians in the management of the disease.

A challenging road to diagnosing transthyretin cardiac amyloidosis and using technetium-99m pyrophosphate bone scintigraphy in nuclear cardiology - A case report

Cardiac amyloidosis (CA) is a rare form of protein deposition disease, leading to restrictive cardiomyopathy that often presents with signs and symptoms of unexplained heart failure with preserved ejection fraction (HFpEF). There are two main subtypes of CA, namely light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR), which are conventionally confirmed by endomyocardial biopsy (EMB). The prognosis and treatment of the subtypes differ extensively, making it crucial to distinguish between the two. Although echocardiography (ECHO) and cardiac magnetic resonance imaging (CMR) are useful to aid in the diagnosis, they are unable to differentiate between the subtypes. Advantageously, the transthyretin cardiac amyloidosis (ATTR-CA) subtype can be diagnosed based on nuclear medicine bone scintigraphy imaging using Technetiumlabelled bone-seeking radiotracers. We report a case of a previously well, elderly gentleman who presented with acute heart failure symptoms, whereby ECHO findings were suspicious for CA. Technetium-99m pyrophosphate (99mTc- PYP) bone scintigraphy performed with complementary single photon emission computed tomography/computed tomography (SPECT/CT) at three hours post-injection revealed radiotracer uptake in the myocardium that was higher than the skeletal bone uptake. This corresponded to Perugini score of 3 along with an increased heart to contralateral lung ratio (H:CL) of 1.69. The bone scintigraphy findings together with his symptoms, ECHO, CMR, and laboratory results enabled the diagnosis of ATTR-CA to be made. In summary, bone scintigraphy offers a reliable and non-invasive method for the diagnosis of ATTR-CA. We also highlight the diagnostic pitfalls and recommendations in reporting bone scintigraphy for the indication of typing cardiac amyloidosis.

AB0856 CHRONIC INTESTINAL PSEUDO-OBSTRUCTION WITH HYDRONEPHROSIS: A CASE REPORT ON SUCH DISABLING AND RARE COMPLICATION OF LUPUS

Background:

Chronic intestinal pseudo-obstruction can be a rare complication of systemic lupus erythematosus. It is often late to be identified in contrast to other commoner organs involvement in systemic lupus erythematosus such as nervous system, joint and kidney.

Objectives:

To report a case of uncommon gastrointestinal complication of lupus, with associated hydronephrosis at the ureter, with treatment delay.

Methods:

We report a case of chronic intestinal pseudo-obstruction.

Results:

A 34 year old, with ten-year history of lupus nephritis, presented with recurrent abdominal pain and diarrhoea past nine months. The patient had just been diagnosed as end-stage renal failure a year ago, on regular haemodialysis. For the past ten years, the patient was not able to tolerate immunosuppressant due to the multiple episodes of infections, including shin carbuncle, herpes zoster, breast abscess and catheter-related candida/bacterial infections. However, the patient did not have any other major organs manifestations of lupus for the past ten years. The patient was apyretic. Multiple stool cultures were negative including Clostridium difficile. The abdominal radiography showed dilated small bowel with diffuse thickening of large and small bowels on computed tomography. Bilateral uretero-hydronephrosis was also noted without any evidence of obstructive uropathy on imaging. Ileocolic resection was done for presumed intestinal obstruction and the ileocolic biopsy did not reveal any granuloma, malignancy or vasculitis except for non-specific inflammation of cecum. Cytomegalovirus inclusion body was absent as well. Tuberculosis culture was negative. Oesophagoduodenoscopy and colonoscopy were offered in view of persistent unexplained loose stool and abdominal pain. But unremarkable findings were noted from multiple biopsy specimens of the small and large bowels. Second relook of the initial hemicolectomy specimen with special actin immunostain on the smooth muscle revealed degenerative changes of the muscularis propria. These were evidenced by cytoplasmic vacuolation, atrophy and pyknotic nucleus of the smooth muscle cells with surrounding oedema. Smooth muscle dysmotility could be the underlying pathology of this patient presentation. The patient responded well to intravenous immunoglobulin followed by azathioprine in addition to prednisolone and prokinetic agent.

Conclusion:

Prompt recognition is pivotal in this case could have prevented the unnecessary surgical intervention earlier. It is potentially reversible. Long term prognosis of this rare entity is, however, varying.

Disclosure of Interests:

None declared

Glomus Tumor of Sella Turcica With Synaptophysin Expression Mimicking Pituitary Adenoma

Glomus tumor can rarely arise in the central nervous system as a sella turcica mass. In this article, we report a case of sellar glomus tumor in a female patient who presented at the age of 8 years with visual impairment. The tumor recurred at 4 years and 26 years after initial excision and gamma knife therapy. Histologic examination showed a monotonous population of oval cells accompanied by delicate blood vessels, features mimicking pituitary adenoma. The tumor showed histologic progression at the second recurrence. Synaptophysin staining was positive, but chromogranin and CD56 were negative. The tumor cells were negative for epithelial markers but expressed actin and SMA. Awareness of the rare occurrence of glomus tumor at this region, careful analysis of morphology, and appropriate immunohistochemical workup are essential to solve this diagnostic challenge. The clinicopathologic features of all previously reported cases are reviewed.

A web-based educational intervention module to improve knowledge and attitudes towards thalassaemia prevention in Malaysian young adults

BACKGROUND

Thalassaemia is a public health burden in Malaysia and its prevention faces many challenges. In this study, we aimed to assess the effectiveness of a web-based educational module in improving knowledge and attitudes about thalassaemia prevention amongst Malaysian young adults.

METHODS

We designed an interactive web-based educational module in the Malay language wherein videos were combined with text and pictorial visual cues. Malaysians aged 18-40 years old who underwent the module had their knowledge and attitudes assessed at baseline, post-intervention and at 6-month follow-up using a selfadministered validated questionnaire.

RESULTS

Sixty-five participants: 47 Malays (72.3%), 15 Chinese (23.1%), three Indians (4.6%) underwent the module. Questionnaires were completed at baseline (n=65), postintervention (n=65) and at 6-month follow-up (n=60). Out of a total knowledge score of 21, significant changes were recorded across three time-points- median scores were 12 at pre-intervention, 19 at post-intervention and 16 at 6-month follow-up (p<0.001). Post-hoc testing comparing preintervention and 6-month follow-up scores showed significant retention of knowledge (p<0.001). Compared to baseline, attitudes at 6-month follow-up showed an increased acceptance for "marriage avoidance between carriers" (pre-intervention 20%, 6-month follow-up 48.3%, p<0.001) and "prenatal diagnosis" (pre-intervention 73.8%, 6-month follow-up 86.2%, p=0.008). Acceptance for selective termination however, remained low without significant change (pre-intervention 6.2%, 6-month follow-up 16.7%, p=0.109).

CONCLUSION

A web-based educational module appears effective in improving knowledge and attitudes towards thalassaemia prevention and its incorporation in thalassaemia prevention programs is potentially useful in Malaysia and countries with a high internet penetration rate.

Skill validation study on sentinel lymph node biopsy in breast cancer and the challenges of false-negative, in-transit and micrometastatic nodes

No abstract available.

Complete 3rd cranial nerve dysfunction postdeflation/ excision of an encasing pituitary macroadenoma intrasellular cyst: A Case Report

Central nervous system injury in particular cranial nerve palsy has been reported to be as high as 2%. Such prevalence of palsy generally attributed to surgical manipulation at the cavernous sinus, especially incurring the abducens nerve. We report the first case of acute oculomotor nerve sequel to the release of cystic fluid wrapping the nerve following a transsphenoidal excision of pituitary macroadenoma in a 57-year-old woman. She attended with the presentation of acute excruciating headache associated with partial drooping of right eye. The computed tomography and magnetic resonance imaging (MRI) were consistent with pituitary apoplexy of an underlying pituitary macroadenoma. Urgent transsphenoidal hypophysectomy was done. Intra-operatively, cystic fluid was aspirated during pituitary tumour dissection. At the same time, curettage was employed to removal residual tumour after the tumour biopsy. Immediate post-operative assessment noted complete right eye ptosis, with clinical evidence of complete right third and fourth nerve palsies. MRI was repeated a week later in view of such palsy non-resolution. However, no local compression or edema noted. Observation and monitoring were opted versus surgical revision. Propitiously the aforementioned cranial nerve palsies persist for a month and subsequently subsided. In this case, we highlight the potential deleterious impact of aspirating cystic component and curettaging during pituitary surgery. Likely postulated accounts for such occurrence include sudden release of fluid pressure with resultant cystic traction on its enfolding cranial nerves and subsequent neuropraxia. We aim to invite comments that could enlighten us on this gray area.

Bibliography of clinical research in malaysia: methods and brief results

This article describes the methodology of this bibliography. A search was conducted on the following: (1) bibliographic databases (PubMed, Scopus, and other databases) using search terms that maximize the retrieval of Malaysian publications; (2) Individual journal search of Malaysian healthrelated journals; (3) A targeted search of Google and Google Scholar; (4) Searching of Malaysian institutional repositories; (5) Searching of Ministry of Health and Clinical Research Centre website. The publication years were limited to 2000- 2013. The citations were imported or manually entered into bibliographic software Refworks. After removing duplicates, and correcting data entry errors, PubMed's Medical Subject Headings (MeSH terms) were added. Clinical research is coded using the definition "patient-oriented-research or research conducted with human subjects (or on material of human origin) for which the investigator directly interacts with the human subjects at some point during the study." A bibliography of citations [n=2056] that fit the criteria of clinical research in Malaysia in selected topics within five domains was generated: Cancers [589], Cardiovascular diseases [432], Infections [795], Injuries [142], and Mental Health [582]. This is done by retrieving citations with the appropriate MESH terms, as follow: For cancers (Breast Neoplasms; Colorectal Neoplasms; Uterine Cervical Neoplasms), for cardiovascular diseases (Coronary Disease; Hypertension; Stroke), for infections (Dengue; Enterovirus Infections, HIV Infections; Malaria; Nipah Virus; Tuberculosis), for injuries (Accidents, Occupational; Accidents, Traffic; Child Abuse; Occupational Injuries), for mental health (Depression; Depressive Disorder; Depressive Disorder, Major; Drug Users; Psychotic Disorders; Suicide; Suicide, Attempted; Suicidal Ideation; Substance- Related Disorders).

Consistency of response and image recognition, pulmonary nodules

OBJECTIVE

To investigate the effect of recognition of a previously encountered radiograph on consistency of response in localized pulmonary nodules.

METHODS

13 radiologists interpreted 40 radiographs each to locate pulmonary nodules. A few days later, they again interpreted 40 radiographs. Half of the images in the second set were new. We asked the radiologists whether each image had been in the first set. We used Fisher's exact test and Kruskal-Wallis test to evaluate the correlation between recognition of an image and consistency in its interpretation. We evaluated the data using all possible recognition levels-definitely, probably or possibly included vs definitely, probably or possibly not included by collapsing the recognition levels into two and by eliminating the "possibly included" and "possibly not included" scores.

RESULTS

With all but one of six methods of looking at the data, there was no significant correlation between consistency in interpretation and recognition of the image. When the possibly included and possibly not included scores were eliminated, there was a borderline statistical significance (p = 0.04) with slightly greater consistency in interpretation of recognized than that of non-recognized images.

CONCLUSION

We found no convincing evidence that radiologists' recognition of images in an observer performance study affects their interpretation on a second encounter.

ADVANCES IN KNOWLEDGE

Conscious recognition of chest radiographs did not result in a greater degree of consistency in the tested interpretation than that in the interpretation of images that were not recognized.

Validation of motion correction techniques for liver CT perfusion studies

OBJECTIVES

Motion in images potentially compromises the evaluation of temporally acquired CT perfusion (CTp) data; image registration should mitigate this, but first requires validation. Our objective was to compare the relative performance of manual, rigid and non-rigid registration techniques to correct anatomical misalignment in acquired liver CTp data sets.

METHODS

17 data sets in patients with liver tumours who had undergone a CTp protocol were evaluated. Each data set consisted of a cine acquisition during a breath-hold (Phase 1), followed by six further sets of cine scans (each containing 11 images) acquired during free breathing (Phase 2). Phase 2 images were registered to a reference image from Phase 1 cine using two semi-automated intensity-based registration techniques (rigid and non-rigid) and a manual technique (the only option available in the relevant vendor CTp software). The performance of each technique to align liver anatomy was assessed by four observers, independently and blindly, on two separate occasions, using a semi-quantitative visual validation study (employing a six-point score). The registration techniques were statistically compared using an ordinal probit regression model.

RESULTS

306 registrations (2448 observer scores) were evaluated. The three registration techniques were significantly different from each other (p=0.03). On pairwise comparison, the semi-automated techniques were significantly superior to the manual technique, with non-rigid significantly superior to rigid (p<0.0001), which in turn was significantly superior to manual registration (p=0.04).

CONCLUSION

Semi-automated registration techniques achieved superior alignment of liver anatomy compared with the manual technique. We hope this will translate into more reliable CTp analyses.

A randomized phase II study of gemcitabine (G) plus the cardiac glycoside huachansu (H) in the treatment of patients with locally advanced (LAPC) or metastatic pancreatic cancer (MPC)

284

Background: Wild toad venom has been used for over 1,000 years as a traditional Chinese medicine; H, the extract of dried toad skin glands, is a potent cardiac glycoside without significant toxicity. H has demonstrated preliminary evidence of antitumor activity in phase I clinical trial evaluation (Cancer 2009, 115:5309-18).

Methods: We conducted a randomized, single-blind, phase II clinical trial of G + H versus G + placebo in patients with LAPC or MPC. Plasma bufalin levels were performed in H-treated subjects. 80 evaluable subjects accrued from October 2007 to May 2010 and were treated with G 1,000mg/m2 (iv on days 1, 8, 15, q 28d) plus either H (20 mL/m2 iv daily for 21 days followed by 7 days off, q 28d) or placebo. Demographic data is demonstrated in the table below.

Results: Grade 3/4 adverse events, objective radiographic response rates (ORR), time to progression (TTP), quality of life (QOL), and overall survival (OS) were similar in the two groups (Table). There was not a statistically significant difference in the average plasma bufalin levels in patients with a radiographic partial response (PR) or stable disease versus those with progressive disease (PD) (0.098 ± 0.093 ng/mL vs. 0.071 ± 0.048 ng/mL, p=0.679).

Conclusions: H when added to G was well tolerated but did not improve OS, TTP, QOL, or ORR. Further investigation of a more potent oral formulation of H is planned. H provided by Shenzhen 999 Traditional Chinese Medicine & Development Co., Ltd. Supported by NIH U19CA121503-01.

[Table: see text]

No significant financial relationships to disclose.

Multimethod imaging, staging, and spectrum of manifestations of metastatic melanoma

The incidence of melanoma has been steadily increasing. Imaging plays an important role in tumour assessment as metastatic melanoma can involve multiple organs. Computed tomography (CT) is currently the most widely used technique for tumour staging, surveillance and assessment of therapeutic response, but ultrasound, magnetic resonance imaging (MRI) and positron-emission tomography (PET)-CT also play important roles in the imaging of this tumour. In this article, we review the pathways of spread, staging according to the recently updated TNM classification, pathology, typical and atypical imaging features at common and uncommon sites, and treatment of metastatic melanoma.

Atypical appendicitis: the impact of CT and its management

Acute appendicitis is a diagnosis that can be made on clinical symptoms and signs but can often be extremely challenging. Difficulties arise particularly when the presentation is atypical, and this can lead to untoward sequelae. In this review, we present the range of presentations of atypical appendicitis, the variety of management options and the potential value of CT.

Minimal-preparation abdomino-pelvic CT in frail and elderly patients: prognostic value of colonic and extracolonic findings

AIM

To examine the overall survival of patients who had had been referred for minimal preparation abdomino-pelvic computed tomography (MPCT), and to assess the prognostic value of the colonic and extracolonic findings detected.

METHODS AND MATERIALS

The survival of a cohort of 1029 elderly and frail patients, with clinical symptoms and signs suspicious for colorectal cancer (CRC), who had undergone MPCT between 1995 and 1998 was investigated. Univariate and multivariate survival analyses were undertaken according to the presence of CRC and extracolonic abnormalities (ECA).

RESULTS

The median age of the 1029 patients was 79.4 years. The overall median survival following MPCT was 5.4 years; and 6.6 years if no abnormality was detected. On multivariate analysis, age, sex, CRC status, and number of ECAs were significant factors in overall survival. Median survival for those with confirmed CRC [n=91 (prevalence, 8.8%)] was 1.1 years, compared with 5.9 years without CRC (p<0.0001); and 2.4 years for those with one or more ECA [n=245 (prevalence, 23.8%)], compared with 6.1 years without ECA (p<0.0001). Survival was progressively shorter for increasing numbers of ECAs; and shorter for previously unknown non-CRC malignancies (n=24) compared with CRC (p<0.0001).

CONCLUSIONS

MPCT appears to have prognostic potential in this patient population, with significant reductions in survival if a CRC or ECA is detected. The detection of ECA would appear to have at least as important an impact on the usefulness of the examination as the detection of CRC.

A phase I dose-escalation study of the safety and pharmacokinetics (PK) of XL184, a VEGFR and MET kinase inhibitor, administered orally to patients (pts) with advanced malignancies

14031

Background: XL184 is a potent orally available small molecule inhibitor of MET and VEGFR2/KDR, and also inhibits KIT, RET, FLT3, and Tie-2. Methods: This is a ph 1 cohort dose escalation study. Pts with advanced malignancies are treated with 2 cycles of XL184 orally daily for 5 consecutive days every 2 weeks. Response is assessed every 8 wks by RECIST criteria and pts with SD or better receive maintenance therapy. Plasma markers of angiogenesis VEGF-A, sVEGFR2 and Ang2 are being analyzed. Results: A total of 25 pts with advanced malignancies have been treated across 7 dose levels: 0.08 to 5.12 mg/kg. A total of 10 pts have had SD lasting > 3 months. Three pts with medullary thyroid carcinoma (one of whom had a documented RET mutation) had substantial reductions in plasma calcitonin. Three pts have had stable disease for over 6 months, including 1 pt with carcinoid (20% decrease in liver metastases) and 1 pt with T- cell lymphoma (on treatment for >12 mos). One pt with papillary renal cell cancer, a disease that sometimes bears activating MET mutations, demonstrated 9% tumor reduction at first restaging. There have been no DLTs to date. Preliminary PK analysis (0.08–1.28 mg/kg) suggests linear PK with average Cmax values 34.2, 70, 198, 322 and 603 ng/mL following the fifth dose at 0.08, 0.16, 0.32, 0.64 and 1.28 mg/kg, respectively. The terminal half-life is 80–90 hrs, resulting in concentrations exceeding 200 ng/mL for 96 hours following the fifth dose at 1.28 mg/kg. Conclusions: XL184 appears generally well tolerated at doses tested to date. XL184 has a long terminal half-life. Early signs of antitumor activity have been observed, at doses not associated with toxicity, in patients with various cancers, including but not limited to those that may have RET (medullary thyroid) or MET (papillary renal) mutations.

No significant financial relationships to disclose.

Female sex and standardized mitomycin-c dose are associated with increased risk of neutropenia after hyperthermic intraperitoneal chemotherapy

15091

Background: Cytoreductive sugery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are being increasingly employed in the managment of peritoneal-based malignancies. Depending on the treatment regimen, neutropenia (NP) is a common and potentially life-threatening early postoperative complication of HIPEC. However, little is known about the incidence or risk factors associated with HIPEC-induced NP. Methods: From January 1993 to October 2006, 120 CRS and HIPEC with mitomycin-c (MMC) were performed in 117 patients with appendiceal neoplasm. NP was defined as an absolute neutrophil count of < 1,000/mm3. Variables assessed as potential risk factors for HIPEC-induced NP included: age, sex, weight, BMI, BSA, splenectomy, dose of MMC (standardized for BSA and nonstandardized), percent of perfusate recovered, length of surgery, estimated blood loss, perioperative blood transfusion, and history of prior chemotherapy. Results: Total perfusate MMC doses ranged between 37.25 and 65 mg. The overall incidence of NP was 39.2%. The NP rates in female and male were 57.6% and 21.3%, respectively. Female sex, BMI, BSA, and the standardized dose of MMC were significantly associated with an increased risk of NP by univariable logistic regression. Female sex and standardized dose of MMC remained statistically significant for an increased risk of NP on multivariable logistic regression. The odds ratio (OR) of NP for females was 3.63 (95% CI: 1.54, 8.52); the OR of NP for a 1 mg/m2 increase in standardized MMC dose was 1.26 (95% CI: 1.11, 1.44). No other variables were identified as independent predictors of increased or decreased risk of NP. Compared to patients without NP, patients with NP had a higher rate of urinary tract infection (42.6% vs. 21.1%, p=0.01) and slightly higher length of stay (median: 24.0 days vs. 18.5 days, p=0.16). Conclusions: NP is a common complication after HIPEC with MMC . Female patients are at significantly increased risk for this complication. Risk of NP also increases with MMC dose standardized for BSA. With increasing interest in the use of CRS and HIPEC, understanding the risk factors for HIPEC-induced NP may facilitate reducing the morbidity associated with this procedure.

No significant financial relationships to disclose.

Analysis of diagnostic confidence and diagnostic accuracy: a unified framework

Diagnostic confidence has been used as a measure of diagnostic efficacy, but this measure in isolation fails to take into account incorrect diagnoses. Conventional analytical approaches of diagnostic confidence ignore associated diagnostic accuracy. To address this limitation, we introduce a unifying framework which incorporates diagnostic confidence, changes in diagnoses and ultimate accuracy. The framework is illustrated using data from a study in which 62 patients with acute abdominal pain prospectively underwent CT. Admitting surgeons documented their diagnoses and graded their diagnostic confidences (on a 5-point scale) on admission and again after CT. Our approach, unlike conventional analyses, incorporates knowledge of final diagnoses, obtained from surgery or 6 months follow up, in assessing the impact of the test (on a 9-point scale). Changes in pre- and post-CT confidence scores were assessed by the one-sample t-test comparing against zero change, with the test statistic acting as a standardized quantity allowing comparison between our and conventional methodological approaches. Overall, 52% (32/62) of patients were misdiagnosed on admission and 19% (12/62) had incorrect post-CT diagnoses. Diagnostic confidence following CT increased significantly compared with pre-CT confidence on applying both analytical methods, although the level of statistical significance was less marked using our approach. Mean (95% confidence interval) increase in confidence under conventional analysis was 1.32 (1.03, 1.62), with standardized score t = 8.90 [p<0.0001], whereas our method yielded 0.69 (0.25, 1.13), with standardized score t = 3.12 [p = 0.003]. Although both analytical methods led to the same inference regarding the efficacy of CT in the illustrative case study presented, they differed somewhat in degree. It is conceivable that disparate conclusions may emerge in other studies and circumstances. Failure to take adequate account of incorrect diagnoses is potentially misleading. We suggest that a comprehensive analysis of diagnostic confidence requires the incorporation of diagnostic accuracy.

Towards comprehensive population-based screening for diabetic retinopathy: operation of the North Wales diabetic retinopathy screening programme using a central patient register and various screening methods

OBJECTIVES

To examine whether population-based retinopathy screening using a central diabetes register and employing various screening methods can achieve a high degree of population coverage to meet National Screening Committee (NSC) targets. To identify the main barriers to achieving comprehensive population coverage. To analyse referrals to ophthalmology and their outcome as a measure of previously unmet need. To assess the influence of modality of screening.

SETTING

Three local health board areas in North Wales.

METHODS

Establishment of a district diabetes register to hold records of all patients and subserve call-recall of general practitioner (GP) sole-care patients for screening by optometrists or digital photography. Hospital attenders were screened in diabetic clinic by direct ophthalmoscopy. Data were collected for years 1 and 2 of operation of the scheme.

RESULTS

The system held a screening record for 86% of diabetic patients after year 1 and 93% after year 2. Failure to attend was the major barrier to comprehensive population screening, but this improved in year 2 (P<0.001). Both optometrists and photography identified substantial unmet need: 1% of all GP sole-care patients required immediate laser treatment. Photography was more sensitive than optometrist screening, but the additional retinopathy identified was mostly minor not requiring treatment.

CONCLUSIONS

Lack of screening is much more important than modality of screening as a cause of missed sight-threatening retinopathy. A central, district-based patient register system identifies those patients not screened for further follow-up and can produce a high level of population coverage, close to NSC targets. Such schemes are needed, particularly to support primary care diabetes management.

Minimal preparation CT for the diagnosis of suspected colorectal cancer in the frail and elderly patient

Colorectal cancer is a common malignancy with an increased incidence in the elderly population. Traditional methods of evaluating this disease have included double contrast barium enema and colonoscopy. Unfortunately, in the frail and elderly patient, these investigations can be difficult to perform and are often not tolerated. Minimal preparation computed tomography (MPCT) of the colon has been suggested as an alternative in this patient population. In this technique, no bowel preparation is used apart from the administration of oral contrast medium. The patient is imaged only in the supine position, without per rectal insufflation of gas or barium. This article reviews the experience to date of MPCT in detecting colonic tumours, and compares its efficacy to the traditional methods. A meta-analysis of the studies allowed estimation of the pooled sensitivity of MPCT to be 83% (95% confidence interval: 76-89%), and pooled specificity to be 90% (95% CI: 85-94%). An added advantage of MPCT is the ability to identify extra-colonic pathology, and this aspect is also reviewed. In addition, the common radiological features and pitfalls in identifying colonic tumours by MPCT are discussed.

Instability of clonality in gastric lymphoid infiltrates: a study with emphasis on serial biopsies

The evolution of low-grade B-cell mucosa-associated lymphoid-tissue (MALT) lymphoma of the stomach is a multistage process, reflected in the histologic continuum from Helicobacter pylori-chronic gastritis, to low-grade and high-grade lymphoma. Interestingly, in daily gastric biopsy sign-out, the authors observed that some biopsies showed monoclonality on polymerase chain reaction (PCR) even though there were no definite histologic features of malignancy and vice versa. To address the question, the authors studied the endoscopic gastric biopsies at first presentation of 46 patients to examine any clonality differences among various histologic patterns within the spectrum of MALT lymphoma evolution. The gastric biopsies were reviewed histologically and graded according to the Wotherspoon-Isaacson histologic scoring system from grade 0 (normal) to grade 5 (MALT lymphoma). The clonality of cases in each grade was determined by performing nested PCR for immunoglobulin heavy chain (IgH) gene rearrangement using FR2/JH and FR3/JH primer sets. The monoclonality rates among different grades were as follows: grade 2, 6.3% (1 of 16); grade 3, 27.3% (3 of 11); grade 4, 83.3% (5 of 6); grade 5, 69.2% (9 of 13). Statistically significant difference of monoclonality rate is demonstrated in histologic grade 4 versus grades 2 and 3, and grade 5 versus grade 2 (P < 0.05, Fisher exact test). The authors went on to examine the progress of disease by following up the clinical status, histologic changes, and clonality fluctuation of these cases. Four of the 8 patients with monoclonality on PCR, but no definite lymphoma at first presentation later progressed to frank MALT lymphoma. Our study shows that, during the progression to MALT lymphoma, there is an instability of clonality. Clonality can fluctuate between polyclonality, oligoclonality, and monoclonality, none of which defines an irreversible stage for progression to MALT lymphoma. Monoclonality is a risk factor for development of MALT lymphoma. Those cases with dense gastric mucosal lymphoid infiltrate (without definite MALT lymphoma) and monoclonality on PCR need to be closely monitored and Helicobacter infection promptly treated if present. In combination with clinicohistologic examination, PCR can serve as a complementary tool in arriving at a definite diagnosis of MALT lymphoma in cases with borderline histologic features.

Bernstein-Greene-Kruskal modes in a three-dimensional plasma

Bernstein-Greene-Kruskal modes in a three-dimensional (3D) unmagnetized plasma are constructed. It is shown that 3D solutions that depend only on energy do not exist. However, 3D solutions that depend on energy and additional constants of motion (such as angular momentum) do exist. Exact analytical as well as numerical solutions are constructed assuming spherical symmetry, and their properties are contrasted with those of 1D solutions. Possible extensions to solutions with cylindrical symmetry with or without a finite magnetic guide field are discussed.