Age-related comorbidities and mortality in people living with HIV in rural Tanzania.

OBJECTIVE: Causes of morbidity and mortality of people living with HIV are changing with access to antiretroviral therapy and increased life expectancy. Age-related data on comorbidities and their impact on mortality in sub-Saharan Africa are scarce. DESIGN: This prospective analysis evaluated comorbidities, assessed by means of International Classification of Diseases and Related Health problems 10th revision codes and clinical variables, derived from data collected from the Kilombero & Ulanga antiretroviral cohort of people living with HIV in rural Tanzania. METHODS: We calculated prevalences and incidences of comorbidities in patients enrolled from 2013 to 2017 and evaluated their association with a combined endpoint of death and loss to follow-up (LTFU) in various age groups (15-29, 30-49 and ≥50 years) using Cox regression analysis. RESULTS: Of 1622 patients [65% females, median age 38 years (interquartile range 31-46)], 11% were at least 50 years. During a median follow-up of 22.1 months (interquartile range 10.6-37.3), 48 (2.9%) patients died and 306 (18.9%) were LTFU. Anaemia was the most prevalent comorbidity (66.3%) irrespective of age and was associated with increased mortality/LTFU [hazard ratios 2.02 (95% confidence interval (CI) 1.57-2.60); P < 0.001]. In patients aged at least 50 years, arterial hypertension was highly prevalent (43.8%), but not associated with mortality/LTFU [hazard ratios 1.04 (95% CI 0.56-1.93), P = 0.9]. Undernutrition ranged from 25.5% in the youngest to 29.1% in the oldest age group and contributed to mortality/LTFU [hazard ratios 2.24 (95% CI 1.65-3.04); P < 0.001]. Prevalence of tuberculosis was 21.4% with hazard ratios of 2.54 (95% CI 1.72-3.75, P < 0.001) for mortality/LTFU. CONCLUSION: We show that anaemia, arterial hypertension and undernutrition are the most relevant comorbidities with different age-associated frequencies and impact on death/LTFU in this population.

Repatriations and 28-day mortality of ill and injured travellers: 12 years of experience in a Swiss emergency department.

QUESTIONS UNDER STUDY: Many persons are travelling all over the world; the elderly with pre-existing diseases also travel to places with less developed health systems. Reportedly, fewer than 0.5% of all travellers need repatriation. We aimed to analyse and examine people who are injured or ill while abroad, where they travelled to and by what means they were repatriated. METHODS: Retrospective cross-sectional study with adult patients repatriated to a single level 1 trauma centre in Switzerland (2000-2011). RESULTS: A total of 372 patients were repatriated, with an increasing trend per year. Of these, 67% were male; the median age was 56 years. Forty-nine percent sustained an injury, and 13% had surgical and 38% medical pathologies. Patients with medical conditions were older than those with injuries or surgical emergencies (p <0.001). Seventy-three percent were repatriated from Europe. For repatriation from Africa trauma was slightly more frequent (53%, n = 17) than illnesses, whereas for most other countries illnesses and trauma were equally distributed. Injured patients had a median Injury Severity Score of 8. The majority of illnesses involved the nervous system (38%), mainly stroke. Forty-five percent were repatriated by Swiss Air Ambulance, 26% by ground ambulance, 18% by scheduled flights with or without medical assistance and two patients injured near the Swiss boarder by helicopter. The 28-day mortality was 4%. CONCLUSIONS: The numbers of travellers repatriated increased from 2000 to 2011. About half were due to illnesses and half due to injuries. The largest group were elderly Swiss nationals repatriated from European countries. As mortality is relatively high, special consideration to this group of patients is warranted.

Are clusters important in understanding the mechanisms in atmospheric pressure ionization? Part 1: Reagent ion generation and chemical control of ion populations.

It is well documented since the early days of the development of atmospheric pressure ionization methods, which operate in the gas phase, that cluster ions are ubiquitous. This holds true for atmospheric pressure chemical ionization, as well as for more recent techniques, such as atmospheric pressure photoionization, direct analysis in real time, and many more. In fact, it is well established that cluster ions are the primary carriers of the net charge generated. Nevertheless, cluster ion chemistry has only been sporadically included in the numerous proposed ionization mechanisms leading to charged target analytes, which are often protonated molecules. This paper series, consisting of two parts, attempts to highlight the role of cluster ion chemistry with regard to the generation of analyte ions. In addition, the impact of the changing reaction matrix and the non-thermal collisions of ions en route from the atmospheric pressure ion source to the high vacuum analyzer region are discussed. This work addresses such issues as extent of protonation versus deuteration, the extent of analyte fragmentation, as well as highly variable ionization efficiencies, among others. In Part 1, the nature of the reagent ion generation is examined, as well as the extent of thermodynamic versus kinetic control of the resulting ion population entering the analyzer region.

Studies of the mechanism of the cluster formation in a thermally sampling atmospheric pressure ionization mass spectrometer.

In this study a thermally sampling atmospheric pressure ionization mass spectrometer is described and characterized. The ion transfer stage offers the capability to sample cluster ions at thermal equilibrium and during this transfer fundamental processes possibly affecting the cluster distribution are also readily identified. Additionally, the transfer stage combines optional collision-induced dissociation (CID) analysis of the cluster composition with thermal equilibrium sampling of clusters. The performance of the setup is demonstrated with regard to the proton-bound water cluster system. The benefit of the studied processes is that they can help to improve future transfer stages and to understand cluster ion reactions in ion mobility tubes and high-pressure ion sources. In addition, the instrument allows for the identification of fragmentation and protonation reactions caused by CID.

Generation of ion-bound solvent clusters as reactant ions in dopant-assisted APPI and APLI.

We provide experimental and theoretical evidence that the primary ionization process in the dopant-assisted varieties of the atmospheric pressure ionization methods atmospheric pressure photoionization and atmospheric pressure laser ionization in typical liquid chromatography-mass spectrometry settings is--as suggested in the literature--dopant radical cation formation. However, instead of direct dopant radical cation-analyte interaction--the broadly accepted subsequent step in the reaction cascade leading to protonated analyte molecules--rapid thermal equilibration with ion source background water or liquid chromatography solvents through dopant ion-molecule cluster formation occurs. Fast intracluster chemistry then leads to almost instantaneous proton-bound water/solvent cluster generation. These clusters interact either directly with analytes by ligand switching or association reactions, respectively, or further downstream in the intermediate-pressure regions in the ion transfer stages of the mass spectrometer via electrical-field-driven collisional decomposition reactions finally leading to the predominantly observed bare protonated analyte molecules [M + H](+).

The role of ion-bound cluster formation in negative ion mass spectrometry.

RATIONALE: The ionization mechanisms operative in negative ion atmospheric pressure mass spectrometry are far from being properly understood. In an excess of oxygen superoxide (O(2)(-)) is generally the primary charge-carrying species that is generated. However, subsequent reactions leading to the finally detected ion signals remain obscure. METHODS: Since adiabatic expansion induced cluster growth and collision-induced dissociation (CID) processes rendered a representative sampling of ion distributions present in the source difficult, a custom-built thermally sampling time-of-flight mass spectrometer was used for the investigations. Using atmospheric pressure laser ionization of toluene as the reagent gas, high yields of thermal electrons were observed, but only negligible amounts of by-products. Ab initio calculations for individual ion/molecule reaction pathways were performed. RESULTS: Electron capture by molecular oxygen resulted in the formation of subsequent superoxide water clusters as well as distinct analyte-adduct ions. By adjusting the extent of CID within the ion optical stages of the mass spectrometer, the cluster distribution changes to smaller cluster sizes and the analyte signals strongly shifted towards M(-) or [M-H](-). The observed superoxide water cluster distribution was close to thermal. The theoretical results confirmed the experimental findings. CONCLUSIONS: In negative atmospheric pressure mass spectrometry the water concentration in the ion source (determining the ionization efficiency) and the CID energy provided through electrical fields (determining the ion distribution) are primary, critical parameters for the observed overall ionization mechanism and efficiency.