Assessing the dynamic changes in vitiligo: reliability and validity of the Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS).

BACKGROUND: The assessment of the individual evolution of vitiligo is important for therapeutic decision making in daily practice. A fast, simple and validated physician-reported score to assess clinical changes in depigmentation over time in separate parts (activity and improvement) is currently missing. OBJECTIVE: The main objective of the study was to develop and validate the Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS). METHODS: The Vitiligo Disease Activity Score (VDAS) and Vitiligo Disease Improvement Score (VDIS) were evaluated based on a photo set of 66 patients with two different time points. In the first (short) version, only the number of changing body regions was counted based on 15 predefined areas (VDAS15 and VDIS15 ), while in the second (extensive) version the degree of worsening or improvement from +4 to -4 for each body area was added for a more detailed assessment (VDAS60 and VDIS60 ). Content and construct validity were tested. In addition inter-, intrarater reliability and feasibility were evaluated by 7 (test) and 5 (retest) physicians. RESULTS: Evidence for content and construct validity was provided. Overall, VDAS15 , VDIS15 , VDAS60 and VDIS60 demonstrated good to excellent inter-rater reliability [intraclass correlation (ICC): VDAS: range = 0.797-0.900; VDIS: range = 0.726-0.798]. The intrarater reliability ICCs were 0.865 and 0.781 for the VDAS15 and VDIS15 , respectively. Similar results were obtained for the VDAS60 and VDIS60 (ICC = 0.913 and 0.800, respectively). Completion time was short (median: 122 s/patient (first round); 95 s/patient (second round)]. LIMITATIONS: Single tertiary centre mainly of skin phototype 2 to 3. CONCLUSION: The VDAS and VDIS appear to be valid, reliable and feasible instruments to score the evolution of vitiligo lesions. This accommodates the current urgent need for a simple, standardized and practical assessment of vitiligo activity and improvement over time.

A novel approach to detect test-seeking behaviour in the blood donor population: making the invisible visible.

BACKGROUND AND OBJECTIVES: Individuals may donate blood in order to determine their infection status after exposure to an increased infection risk. Such test-seeking behaviour decreases transfusion safety. Instances of test seeking are difficult to substantiate as donors are unlikely to admit to such behaviour. However, manifestation in a population of repeat donors may be determined using statistical inference. MATERIALS AND METHODS: Test-seeking donors would be highly motivated to donate following infection risk, influencing the timing of their donation. Donation intervals within 2005-2014 of all Dutch blood donors who acquired syphilis (N = 50), HIV (N = 13), HTLV (N = 4) or HCV (N = 2) were compared to donation intervals of uninfected blood donors (N = 7 327 836) using the Anderson-Darling test. We adjusted for length bias as well as for age, gender and donation type of the infected. Additionally, the power of the proposed method was investigated by simulation. RESULTS: Among the Dutch donors who acquired infection, we found only a non-significant overrepresentation of short donation intervals (P = 0·54). However, we show by simulation that both relatively short and long donation intervals among infected donors can reveal test seeking. The power of the method is >90% if among 69 infected donors >35 (51%) are test seeking, or if among 320 infected donors >90 (30%) are test seeking. CONCLUSION: We show how statistical analysis may be used to reveal the extent of test seeking in repeat blood donor populations. In the Dutch setting, indications for test-seeking behaviour were not statistically significant. This may, however, be due to the low number of infected individuals.

Benefits of hepatitis C virus treatment: a balance of preventing onward transmission and re-infection.

By treating HCV-infected injecting drug users (IDUs), we may prevent infections to other IDUs. Curing preferentially individuals who most often share injecting equipment has the advantage of preventing more infections. However, such high risk behavior IDUs are also more likely to become re-infected. We have created a model that can inform us about most efficient HCV treatment policy; the expected benefits per treatment of one HCV-infected IDU are calculated, defined as a decrease in the number of chronic HCV infections. This includes the probability that the cured IDU remains uninfected, and the number of new infections prevented both directly and indirectly in further infection generations. We explore analytically how these benefits depend on the syringe sharing frequency of the cured IDU. We find that whom to best cure is determined by the prevalence of HCV contamination among exchanged syringes within the IDU population. Treating lowest risk IDUs is most beneficial above a certain prevalence of contamination, since the term for re-infection dominates the equation in this domain. At lower prevalence treating highest risk IDUs is most beneficial, since here the term for prevention dominates. In a much simplified model the threshold between domains is found at exactly 50% HCV prevalence. The threshold value is lowered when taking HCV induced mortality or increased infectiousness during an acute stage of infection into account. It is increased when taking into account treatment duration, or when HCV-treatment is combined with intervention that reduces the syringe sharing rate of the cured IDU.