Diagnostic accuracy of serological diagnosis of hepatitis C and B using dried blood spot samples (DBS): two systematic reviews and meta-analyses

Background

Dried blood spots (DBS) are a convenient tool to enable diagnostic testing for viral diseases due to transport, handling and logistical advantages over conventional venous blood sampling. A better understanding of the performance of serological testing for hepatitis C (HCV) and hepatitis B virus (HBV) from DBS is important to enable more widespread use of this sampling approach in resource limited settings, and to inform the 2017 World Health Organization (WHO) guidance on testing for HBV/HCV.

Methods

We conducted two systematic reviews and meta-analyses on the diagnostic accuracy of HCV antibody (HCV-Ab) and HBV surface antigen (HBsAg) from DBS samples compared to venous blood samples. MEDLINE, EMBASE, Global Health and Cochrane library were searched for studies that assessed diagnostic accuracy with DBS and agreement between DBS and venous sampling. Heterogeneity of results was assessed and where possible a pooled analysis of sensitivity and specificity was performed using a bivariate analysis with maximum likelihood estimate and 95% confidence intervals (95%CI). We conducted a narrative review on the impact of varying storage conditions or limits of detection in subsets of samples. The QUADAS-2 tool was used to assess risk of bias.

Results

For the diagnostic accuracy of HBsAg from DBS compared to venous blood, 19 studies were included in a quantitative meta-analysis, and 23 in a narrative review. Pooled sensitivity and specificity were 98% (95%CI:95%–99%) and 100% (95%CI:99–100%), respectively. For the diagnostic accuracy of HCV-Ab from DBS, 19 studies were included in a pooled quantitative meta-analysis, and 23 studies were included in a narrative review. Pooled estimates of sensitivity and specificity were 98% (CI95%:95–99) and 99% (CI95%:98–100), respectively. Overall quality of studies and heterogeneity were rated as moderate in both systematic reviews.

Conclusion

HCV-Ab and HBsAg testing using DBS compared to venous blood sampling was associated with excellent diagnostic accuracy. However, generalizability is limited as no uniform protocol was applied and most studies did not use fresh samples. Future studies on diagnostic accuracy should include an assessment of impact of environmental conditions common in low resource field settings. Manufacturers also need to formally validate their assays for DBS for use with their commercial assays.

     

Screen‐detected colorectal cancers show improved cancer‐specific survival when compared with cancers diagnosed via the 2‐week suspected colorectal cancer referral guidelines

Aim Biennial screening for colorectal cancer using faecal occult blood testing has been shown to reduce the relative risk of mortality from colorectal cancer. The Norwich screening centre commenced screening in July 2006 and so far has diagnosed over 350 patients with colorectal cancer. We compared the stage at diagnosis and cancer‐specific mortality and survival in patients diagnosed through screening with a cohort of symptomatic patients with colorectal cancer within the same age range. Method A comparative analysis was undertaken of all screen‐detected colorectal cancer patients diagnosed between July 2006 and December 2010, with an age‐matched group of patients diagnosed in the Norfolk and Norwich Hospital through the 2‐week suspected colorectal cancer guidelines. Results Three hundred and fifty‐six cases of colorectal cancer were diagnosed through the screening programme, in patients with an age range of 60–79 years. In the same time period, 292 patients in the same age range were diagnosed with colorectal cancer through the 2‐week suspected colorectal cancer pathway. Sixteen patients in the screening group had evidence of metastatic disease at presentation compared with 62 in the symptomatic group (χ², P < 0.001). The proportion of T1/T2 and Dukes A cancers was significantly greater in the screening group (χ², P < 0.001). There were 21 colorectal cancer‐related deaths in the screening group compared with 66 in the symptomatic group. Survival analysis curves showed significantly better survival in the screening group (log‐rank analysis P < 0.001). Conclusion Screening for colorectal cancer identifies cancers at a significantly earlier stage than in symptomatic patients, with subsequent improvement in cancer‐specific survival.     

Motor skills,cognition, and work performance of people with severe mental illness

Purpose: Employment offers many benefits to people with mental illness, yet their employment rate is much lower than that of the general population. We investigated the effect of work-related motor skills, neurocognition, and job attitudes on the work performance of people with mental illness, comparing those working in sheltered workshops, with controls working in similar jobs.

Methods: Twenty-nine adults with severe mental illness and 27 controls matched by gender and age were enrolled into the study using convenience sampling. They were assessed for gross and fine motor hand functioning, job attitudes, work performance, and cognition.

Results: People with mental illness scored lower on work performance, cognitive functioning, and hand dexterity while sitting and working with tools. They were assigned lower job loads than were controls, and perceived the physical environment at work as more constraining than did controls. Assembling motor skills significantly explained the work performance of people with mental illness.

Conclusions: The results expand our understanding of the complexities involved in the employment of people with severe mental illness, and point to new paths for improving vocational outcomes of people with severe mental illness, taking into account their motor skills and job attitudes.

• Implications for rehabilitation

• Therapists should be aware that employed people with severe mental illness may have various unmet needs, affecting their work performance and experience of stress.

• This study results demonstrate importance of motor skills and perception of the work environment for the promotion of vocational outcomes among individuals with severe mental illness.

• Employment of people with severe mental illness should be viewed from holistic perspective as with general population, rather than focused on traditionally illness-related factors.