Identifying domains of health-related quality of life: the perspective of individuals with low back pain

BACKGROUND

Identifying the most relevant HRQOL domains for LBP from the perspective of individuals with lived experience with LBP is necessary to prioritize domains that will be most informative for evaluating the impact of pain and interventions while overcoming the burden of using long-form assessment tools. This study aimed to identify which domains of HRQOL are most important from the perspective of individuals with chronic LBP.

METHODS

Semi-structured interviews were conducted with 26 individuals with LBP. Participants first responded to questions related to the impact of their LBP on their HRQOL. Then, using a card sorting method, they were asked to select and indicate HRQOL domains that were most relevant to them from a list of 18 cards that represented different HRQOL domains. Participants were asked to explain the reasoning for their selection.

RESULTS

Participants identified physical activity restriction (50%), severity of pain (31%), social activity restriction (23%), and work performance restriction (23%) as the most important domains. The most frequently selected HRQOL domains during card sorting were social function (69%), pain intensity (62%), physical function (58%), fatigue (58%), and pain interference (42%).

CONCLUSION

The most important domains of HRQOL perceived by participants were pain intensity, social function, physical function, fatigue, and pain interference. Identifying these domains will inform clinical decision-making and guide treatment choices for health care providers.

Evaluation of the true effect of experimental parameters on the reduction / oxidation processes observed in fast-atom bombardment/liquid secondary spectrometry

The peak intensities observed in the molecular ion regions of fast-atom bombardment/liquid secondary ion mass spectra contain contributions from the parent ion species, its one- and two-electron reduction/oxidation products, and chemical background signal due to beaminduced damage. There are several solution and instrumental parameters that can affect the distribution of peak intensities in the molecular ion region. In this study, the analyte concentration and primary beam density and energy were varied systematically to investigate their effects on the measured peak intensities. A computer algorithm, Simbroc (Simulated Background and Reduction/Oxidation Calculations), was designed to deconvolute the observed intensities into their individual components so that the true effects of experimental parameters on redox extent and background levels could be evaluated. The algorithm is based on a comprehensive seven-variable mathematical model for experimental data simulation. The results obtained using the algorithm after its validation indicate that the primary beam energy does not significantly affect redox extent or background levels. Changes in analyte concentration and primary beam density tend to play a more important role in the generation of redox products and beam-induced damage. The background level generally increases as the analyte concentration is lowered for the peptide systems used in this study. An increase in the primary beam density often leads to higher background levels, although the effect is less detectable for samples that have a low (less than 3%) background signal. The apparent two-electron reduction is generally lower at the higher concentrations; however, the "true" reduction occurring for pentaphenylalanine does not show a significant concentration effect.

Determination of the primary structure of peptides using fast atom bombardment mass spectrometry

The determination of the amino acid composition and sequence of a peptide, using both conventional and tandem fast atom bombardment mass spectrometry, is presented. First a list of potential empirical formulae is generated using the accurate mass and isotopic peak intensity ratios from the molecular ion cluster. The formulae are mathematically analyzed to ensure that they correspond to linear peptides composed of 19 common amino acids. Then using the ions below m/z 160 Da, which are characteristic of the amino acid content of the peptide, the formulae are decomposed into possible amino acid compositions. From each composition sequences are generated and their predicted fragment ions are compared to ions present in the mass spectrum. A score based on the intensities and the occurrence of consecutive sequence fragments is calculated. Finally sequences with the ten highest scores are retained. Analyses performed on typical peptides with molecular weights below 1500 Da indicate that identification can generally be achieved using this approach.

Determination of the empirical formula of peptides by fast atom bombardment mass spectrometry

A method for calculating the empirical formulae of peptides from mass spectrometric data is described. Exact mass measurement data and isotopic peak ratios are used to generate a list of potential empirical formulae that fit a given compound within experimental error. The formulae are then analysed by a mathematical algorithm and only those corresponding to chain peptides formed from the basic amino acids are retained. Calculations conducted for typical peptides indicate that the approach may be useful for peptide identification if the experimental values are determined within an acceptable range of errors. Experimental measurements of the exact mass and isotopic peak ratios made using typical peptides demonstrate the feasibility of the approach.