The selection of search sources influences the findings of a systematic review of people’s views: a case study in public health

Background For systematic reviews providing evidence for policy decisions in specific geographical regions, there is a need to minimise regional bias when seeking out relevant research studies. Studies on people’s views tend to be dispersed across a range of bibliographic databases and other search sources. It is recognised that a comprehensive literature search can provide unique evidence not found from a focused search; however, the geographical focus of databases as a potential source of bias on the findings of a research review is less clear. This case study describes search source selection for research about people’s views and how supplementary searches designed to redress geographical bias influenced the findings of a systematic review. Our research questions are: a) what was the impact of search methods employed to redress potential database selection bias on the overall findings of the review? and b) how did each search source contribute to the identification of all the research studies included in the review? Methods The contribution of 25 search sources in locating 28 studies included within a systematic review on UK children’s views of body size, shape and weight was analysed retrospectively. The impact of utilising seven search sources chosen to identify UK-based literature on the review’s findings was assessed. Results Over a sixth (5 out of 28) of the studies were located only through supplementary searches of three sources. These five studies were of a disproportionally high quality compared with the other studies in the review. The retrieval of these studies added direction, detail and strength to the overall findings of the review. All studies in the review were located within 21 search sources. Precision for 21 sources ranged from 0.21% to 1.64%. Conclusions For reducing geographical bias and increasing the coverage and context-specificity of systematic reviews of people’s perspectives and experiences, searching that is sensitive and aimed at reducing geographical bias in database sources is recommended

Discriminatory ability of calcaneal quantitative ultrasound in the assessment of bone status in patients with inflammatory bowel disease

A high incidence of bone disease in patients with inflammatory bowel disease (IBD) requires frequent monitoring of skeletal status and, for that reason, evaluation of radiation-free technology is an issue of interest. Our objective was to appraise the parameters of calcaneal quantitative ultrasound (QUS): broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness index (QUI), and establish their t-score values to investigate discriminatory ability of QUS in IBD patients with metabolic bone disease. The study included 126 patients (Crohn's disease [n = 94] and ulcerative colitis [n = 32]), and 228 age- and sex-matched healthy volunteers. Bone status was evaluated on the same day by calcaneal QUS and dual-energy x-ray absorptiometry (DXA) at spine (L1-L4) and total hip. All QUS measurements were lower in patients compared with healthy controls (BUA p < 0.001; SOS p < 0.001; QUI p < 0.001) and correlated significantly but inversely with disease duration (r = -0.3, p = 0.002). There was no difference with respect to type of disease (Crohn's disease or ulcerative colitis) or corticosteroid therapy. All three QUS t-scores were significantly lower in patients who had previously sustained fragile fractures (n = 28) than in those without fracture in their history (n = 98) (t-scores: BUA -2.0 vs. -1.3, p = 0.008; SOS -2.1 vs. -1.4, p = 0.02: QUI -2.3 vs. -1.5, p = 0.009). Axial DXA was not significantly different between the fracture and nonfracture patients (-1.7 vs. -1.2, p = 0.1), whereas total hip DXA showed a discriminatory power between the two (-1.6 vs. -0.7, p = 0.001). Patients with t-score < -1.0 scanned by DXA were classified as bone disease. The sensitivity of QUS to identify bone disease was 93% and specificity 63%. The sensitivity of QUS to detect osteopenia was 84% and 72% for osteoporosis. Alternatively, lower negative QUS t-score cutoff </= -1.8 identified 83% of osteoporosis at lumbar spine and 100% at total hip. All three QUS variables had t-scores less than -1.8 when osteoporosis was detected at both spine and hip. However, the subgroup of IBD patients with QUI t-score cutoff </= -1.8 still included 26% of individuals with normal bone status. Calcaneal QUS measurements may identify patients with IBD who are at a higher risk of fracture independently of DXA measurements. However, QUS showed poor agreement with bone status scanned by DXA and a low discriminatory power between osteopenia and osteoporosis