Comparison of normalisation methods for surface-enhanced laser desorption and ionisation (SELDI) time-of-flight (TOF) mass spectrometry data

Background  

Mass spectrometry for biological data analysis is an active field of research, providing an efficient way of high-throughput proteome screening. A popular variant of mass spectrometry is SELDI, which is often used to measure sample populations with the goal of developing (clinical) classifiers. Unfortunately, not only is the data resulting from such measurements quite noisy, variance between replicate measurements of the same sample can be high as well. Normalisation of spectra can greatly reduce the effect of this technical variance and further improve the quality and interpretability of the data. However, it is unclear which normalisation method yields the most informative result.     

Financial incentives and deposit contracts to promote HIV retesting in Uganda: A randomized trial

BackgroundFrequent retesting for HIV among persons at increased risk of HIV infection is critical to early HIV diagnosis of persons and delivery of combination HIV prevention services. There are few evidence-based interventions for promoting frequent retesting for HIV. We sought to determine the effectiveness of financial incentives and deposit contracts in promoting quarterly HIV retesting among adults at increased risk of HIV.Methods and findingsIn peri-urban Ugandan communities from October to December 2018, we randomized HIV–negative adults with self-reported risk to 1 of 3 strategies to promote HIV retesting: (1) no incentive; (2) cash incentives (US$7) for retesting at 3 and 6 months (total US$14); or (3) deposit contracts: participants could voluntarily deposit US$6 at baseline and at 3 months that would be returned with interest (total US$7) upon retesting at 3 and 6 months (total US$14) or lost if participants failed to retest. The primary outcome was retesting for HIV at both 3 and 6 months. Of 1,482 persons screened for study eligibility following community-based recruitment, 524 participants were randomized to either no incentive (N = 180), incentives (N = 172), or deposit contracts (N = 172): median age was 25 years (IQR: 22 to 30), 44% were women, and median weekly income was US$13.60 (IQR: US$8.16 to US$21.76). Among participants randomized to deposit contracts, 24/172 (14%) made a baseline deposit, and 2/172 (1%) made a 3-month deposit. In intent-to-treat analyses, HIV retesting at both 3 and 6 months was significantly higher in the incentive arm (89/172 [52%]) than either the control arm (33/180 [18%], odds ratio (OR) 4.8, 95% CI: 3.0 to 7.7, p < 0.001) or the deposit contract arm (28/172 [16%], OR 5.5, 95% CI: 3.3 to 9.1, p < 0.001). Among those in the deposit contract arm who made a baseline deposit, 20/24 (83%) retested at 3 months; 11/24 (46%) retested at both 3 and 6 months. Among 282 participants who retested for HIV during the trial, three (1%; 95%CI: 0.2 to 3%) seroconverted: one in the incentive group and two in the control group. Study limitations include measurement of retesting at the clinic where baseline enrollment occurred, only offering clinic-based (rather than community-based) HIV retesting and lack of measurement of retesting after completion of the trial to evaluate sustained retesting behavior.ConclusionsOffering financial incentives to high-risk adults in Uganda resulted in significantly higher HIV retesting. Deposit contracts had low uptake and overall did not increase retesting. As part of efforts to increase early diagnosis of HIV among high-risk populations, strategic use of incentives to promote retesting should receive greater consideration by HIV programs.Trial registrationclinicaltrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT02890459","term_id":"NCT02890459"}}NCT02890459.

Gabriel Chamie and colleagues report on a trial of financial incentives for testing in people at risk of HIV infection.