Prospective real-world analysis of OnabotulinumtoxinA in chronic migraine post-National Institute for Health and Care Excellence UK technology appraisal

BACKGROUND AND PURPOSE

The National Institute for Health and Care Excellence (NICE) in the UK recommends the use of OnabotulinumtoxinA (BoNTA, Botox^® ) in the management of chronic migraine (CM) following specific guidelines within the National Health Service. In view of the lack of data on the efficacy of this therapy following implementation of these guidelines in clinical practice and on the evaluation of guidance compliance, we aimed to evaluate the effectiveness and safety of BoNTA in patients with CM following the NICE guidelines.

METHODS

This was a prospective real-life audit study.

RESULTS

After two treatments, 127 of 200 patients (63.5%) obtained at least a 30% reduction in headache days. Those who continued the treatment up to 3 years reported a stable beneficial effect compared with baseline. Amongst responders, 68 patients (53.5%) were reclassified as episodic migraineurs. A total of 57 of these patients (83.8%) converted to an episodic migraine pattern at 6-month follow-up. The majority of those whose migraine became episodic after BoNTA extended the treatment intervals beyond 3 months (range 4-8 months) before noticing any worsening of headache. We observed no significant differences in the efficacy measures in patients treated with 155 U BoNTA compared with those treated with >155 U BoNTA.

CONCLUSIONS

When administered according to the NICE guidance, BoNTA produced a clinically meaningful effect in the long-term management of CM with and without medication overuse headache. Treatment discontinuation when CM becomes episodic may be useful in clinical practice to identify those who may benefit from extended treatment intervals. Our clinical experience indicates a lack of additional benefit from using the 'follow-the-pain' paradigm.

Development of a decision-support tool for identifying the most suitable approach to achieve nitrate source determination

Numerous approaches have been suggested for differentiating point and diffuse sources of nitrate contamination, including nitrate stable isotopes, microbiological analyses, genetic markers and chemical markers. Each approach has its own strengths and limitations. As a result, the most appropriate approach to use largely depends upon the scenario and the context of the study. However, available data on nitrate source determination is highly fragmented and approach dependent, with very little if any interface between the different techniques. This makes it difficult for stakeholders to identify the most suitable approach to adopt in a specific scenario. Therefore, this paper examines the development and application of a decision-support tool to support environmental forensics studies for nitrate contamination. In particular, this tool can support policy makers, regulators and operators within the field in understanding the environmental hazards and processes resulting from nitrate contamination, and to implement appropriate actions for limiting the impacts that may arise from such contamination. The tool was developed using the IDEF0 modeling system, and evaluated by interviewing key stakeholders who suggested a number of important implications for practice.

The potential for a suite of isotope and chemical markers to differentiate sources of nitrate contamination: a review

Nitrate is naturally found within the environment as part of the nitrogen cycle. However, anthropogenic inputs have greatly increased nitrate loads within ground and surface waters. This has had a severe impact on aquatic ecosystems and has given rise to health considerations in humans and livestock. Therefore, the identification of nitrate sources is important in preserving water quality and achieving sustainability of our water resources. Nitrate sources can be determined based on the nitrate nitrogen (N) and oxygen (O) isotopic compositions (δ(15)N, δ(18)O). However, sewage and manure have overlapping δ(15)N and δ(18)O values making their differentiation on this basis problematic. The specific differentiation between sources of faecal contamination is of particular importance, because the risk to humans is usually considered higher from human faecal contamination (sewage) than from animal faecal contamination. This review summarises the current state of knowledge in using isotope tracers to differentiate various nitrate sources and identifies potential chemical tracers for differentiating sewage and manure. In particular, an in depth review of the current state of knowledge regarding the necessary considerations in using chemical markers, such as pharmaceuticals and food additives, to differentiate sewage and manure sources of nitrate contamination will be given, through an understanding of their use, occurrence and fate, in order to identify the most suitable potential chemical markers.

[Cholera epidemic in Senegal in 1995-1996: an example of geographic approach to health]

There have been many cholera outbreaks in Senegal since 1971. The last outbreak began in the Dakar region in August 1995. It spread to the Diourbel, Fatick, Saint-Louis and Thies regions. In January 1996, the outbreak hit the Niakhar study area in the Fatick region. A team from ORSTOM (the French Institute of Scientific Research for Development in Cooperation) has been recording demographic events in this area for almost 15 years. The geographic approach is based on the automated mapping of cholera in hamlets and villages. Such studies investigate the factors determining the spread of diseases, within the context of land use. Three sets of data were used: demographic data that had been routinely collected and were available from a database, digitized maps and epidemiological data from a surveillance system set up to monitor the outbreak. A series of incidence maps, over time and on various scales, were generated using specialized software. The maps were analyzed and the outbreak was found to be heterogeneous over time. There were two waves of the outbreak and differences according to age and gender. The degree of heterogeneity depended on the place of residence. Heterogeneity was probably determined by village size, roads and the concentration of inhabitants within hamlets, which is roughly equivalent to the number of people per bore hole. These preliminary results suggest that further research is necessary, looking at different geographical scales (e.g. households, districts and regions). Qualitative studies of water use and the organization of the water supply are also required.

Chloride current activated by hypotonicity in cultured human astrocytoma cells

Cultured astrocytoma cells were voltage clamped with pipettes where [Ca2+] in the pipette was buffered to 10(-7) M with 10 mM 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and membrane currents recorded. In isotonic solution predominantly K+ currents were evoked by depolarizing or hyperpolarizing commands and 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS; 1 mM) had little effect on inward and outward currents evoked by voltage steps to negative and positive potentials. If the osmolarity of the bathing solution was reduced from 280 to 200 mosmol l-1, a large current developed, which rectified outwardly and reversed close to the equilibrium potential for chloride ions, ECl. Upon stepping to potentials positive to about +30 mV in hypotonic solution, this outward current inactivated over 2-3 s; this decline was greater with N-methyl-D-glucamine chloride (NMDG-Cl) in the pipette than when KCl or sodium glutamate was present. Holding at various positive potentials inactivated the current, with half-inactivation occurring around +50 mV. The current reactivated over 2-3 s at potentials negative to about +30 mV. The current evoked by hypotonic solution was inhibited by various putative chloride channel blockers with the order of potency DIDS > SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid) approximately NPPB (5-nitro-2-(3-phenylpropylamino)-benzoic acid) > niflumic acid > 9-AC (anthracene 9-carboxylic acid). The currents inhibited by these compounds reversed close to the calculated ECl. It is concluded that hypotonic solution evokes a large anionic current in these cultured astrocytoma cells largely carried by chloride ions. This current is absent in isotonic solution, when currents are carried mainly by potassium ions. It is likely that the current elicited by hypotonic solution is part of the mechanisms regulating astrocyte volume in vivo.