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Ian Williamson

Publications and source records attributed to Ian Williamson.

14 recordsLinked to original sources
PubMed2006

Consultations for middle ear disease, antibiotic prescribing and risk factors for reattendance: a case-linked cohort study.

BACKGROUND: Otitis media is the most common reason for children to receive antibiotics, but there is no evidence about the effect of prescribing on reattendance. AIM: To evaluate the changing workload of middle ear disease in general practice, and the impact on surgery reattendance of prescribing antibiotics at first attendance. DESIGN OF STUDY: A case-linked cohort analysis for antibiotic prescribing versus no prescribing at first consultation event. SETTING: Two hundred and ninety-one practices spread throughout the UK recording for the General Practice Research Database (GPRD) and incorporating individual patient data records for 2,265,574 patients. METHOD: All middle ear disease coded events that can be classed within acute otitis media (AOM) or glue ear sub-categories (and excluding chronic suppurative otitis media) were selected for analysis when the first event was from 1991-2001. The effect of antibiotic prescription on the risk of reattendance using Cox proportional hazards regression was analysed. RESULTS: Total consultations for AOM have fallen markedly over this decade, and glue ear consultations have risen but by a much smaller extent (26,000 decrease versus 4000 increase in consultations per year), which makes relabelling an unlikely explanation of the fall in AOM consultations. In the 2-10 years age range, consultations for AOM fell from 105.3 to 34.7 per 1000 per year, with glue ear consultations unaltered (15.2 to 16.7 per 1000 per year). Antibiotic prescribing for AOM has stayed remarkably constant (80-84% of consultations), but antibiotic prescribing for glue ear has risen sharply (13 to 62%). Prescribing antibiotics increased the risk of reattendance for AOM (hazard ratio [HR] = 1.09, 95% confidence interval [CI] = 1.07 to 1.10) and has reduced the risk of reattendance for glue ear (HR = 0.92, 95% CI = 0.88 to 0.96). CONCLUSION: Prescribing antibiotics for AOM probably increased reattendance, but the opposite effect has been noted for glue ear, which suggests a treatment effect of antibiotics in glue ear. Further research is needed to clarify whether this possible benefit is worth the known harms, and if so in which subgroups of children.

Adolescent↗
PubMed2006

Longer term outcomes from a randomised trial of prescribing strategies in otitis media.

BACKGROUND: There are limited data about the longer-term outcomes in acute otitis media (AOM) when comparing the realistic alternatives of immediate prescription of antibiotics and a 'wait and see' or delayed prescribing policy. AIM: The aim was to assess the medium and longer term outcomes of two prescribing strategies for otitis media. DESIGN OF STUDY: Follow-up of a randomised controlled trial cohort. SETTING: Primary care. METHOD: Three-hundred and fifteen children aged 6 months to 10 years presenting with AOM were randomised to immediate antibiotics, or antibiotics delayed at the parents discretion 72 hours if the child still had significant otalgia or fever, or was not improving. Episodes of earache since study entry were documented, and a poor score (of 9 or more--the top 20%) on a reliable six-item functional rating scale (Cronbach's alpha = 0.75). RESULTS: The delayed prescribing strategy did not significantly increase reported episodes of earache in the 3 months since randomisation (odds ratio [OR] = 0.89; 95% confidence interval [CI] = 0.48 to 1.65) or over 1 year (OR = 1.03; 95% CI = 0.60 to 1.78) nor of poor scores on the function scale at 3 months (OR = 1.16; 95% CI = 0.61 to 2.22) or 1 year (OR = 1.12; 95% CI = 0.57 to 2.19), and controlling for subsequent antibiotic use after the randomised episode did not alter these estimates. The number of prior episodes of AOM documented in the doctor's notes predicted episodes of earache reported (0, 1, > or = 2 episodes, respectively; OR = 1, 2.42, 2.61; chi2 for trend 8.04; P<0.01). There was weaker evidence that prior episodes also predicted poor function at 1 year (OR = 1, 1.86, 2.28; chi2 for trend 5.49; P = 0.019). For children with recurrent AOM (two or more previous episodes documented in the doctor's notes, n = 43) there was possible evidence of fewer episodes of earache in the 3 months since study entry in the immediate antibiotic group (10% compared to 39% in the delayed group, chi2 4.8, P = 0.029), but no effect from randomisation to 1 year. CONCLUSIONS: For most children, delayed prescribing is not likely to have adverse longer-term consequences. Children with recurrent AOM are more likely to have poorer outcomes. Secondary analysis should be treated with caution and requires confirmation, but suggests that treating such children with antibiotics immediately may not alter longer-term outcomes.

Amoxicillin↗
PubMed2005

On the relationship between D(ow) and K(ow) in natural waters.

The relationship between the overall octanol-water partition coefficient of a mixture of related chemical species, D(ow), and the octanol-water partition coefficients of its components, (K(ow))i, is explored. One form of the relationship (model 1) is generally applicable but relies on definition of aqueous phase speciation at equilibrium with octanol. An alternative form of the relationship (model 2) circumvents this requirement but assumes that related species are conserved during the partitioning process and is explicitly dependent on the water to octanol volume ratio, Vw/Vo. The potential applications and limitations of each model for defining the hydrophobic characteristics of chemical species in natural waters are examined in the light of experimental partition results for dissolved Cu and Pb in river waters. Given the general difficulties in accurate speciation modeling of trace metals in natural samples, model 1 was only able to estimate a K(ow) (typically in the range 0.03-0.3) for a computed organically complexed fraction of metal (generally > 90%). However, by conducting partition "isotherms" as a function of Vw/Vo and, because of the buffering capacity of natural waters, by treating a sample as two distinct hydrophilic and hydrophobic "pools", model 2 was able to estimate both the abundance and K(ow) of a more specific group of species. Parameter values derived from the latter approach indicated that river waters comprise a relatively small pool (about 4-20%) of metal whose octanol-water partitioning is in the region of 15-150. Given that the free ion activity of strongly binding metals in natural waters is extremely small, the hydrophobic fraction may, in many cases, representthe most biologically and environmentally significant component of metal. Accordingly, the experimental and modeling approaches described herein could be of great significance to an improved understanding of the fate and impacts of trace metals in the aquatic environment.

Copper↗
PubMed2005

Octanol-water partitioning of chemical constituents in river water and treated sewage effluent.

A shake-flask approach has been employed to determine the n-octanol-water partitioning of chemical constituents in various river waters and in treated sewage effluent. The bulk inorganic composition of the water samples (conductivity, pH and the concentrations of major solutes: Ca, K, Mg, Na) was unaffected by the presence of solvent. Boron, however, exhibited increasing partition with decreasing sample pH, because its dominant form in freshwaters, B(OH)3, is neutral, covalent and acidic. Constituents having significant association with dissolved organic matter (DOM), including components of DOM itself (C, S) and trace metals that form complexes with organic ligands (Al, Cu, Fe, Pb, Zn), exhibited measurable partition into the solvent in most cases, with conditional partition coefficients, D(ow), in the region 0.03-2.5. Significant differences in the partitioning among these constituents and among the environments studied did not appear to be related to bulk sample characteristics or the degree of association of the constituent with DOM. These observations suggest that partition is sensitive to the nature of the organic matter (C, S) and the availability of specific binding ligands (trace metals). Thus, although D(ow) is critical for defining the biogeochemical behaviour and potential impacts of chemical constituents in the environment, it appears to be a difficult parameter to model or predict.

1-Octanol↗
PubMed2005

Information leaflet and antibiotic prescribing strategies for acute lower respiratory tract infection: a randomized controlled trial.

CONTEXT: Acute lower respiratory tract infection is the most common condition treated in primary care. Many physicians still prescribe antibiotics; however, systematic reviews of the use of antibiotics are small and have diverse conclusions. OBJECTIVE: To estimate the effectiveness of 3 prescribing strategies and an information leaflet for acute lower respiratory tract infection. DESIGN, SETTING, AND PATIENTS: A randomized controlled trial conducted from August 18, 1998, to July 30, 2003, of 807 patients presenting in a primary care setting with acute uncomplicated lower respiratory tract infection. Patients were assigned to 1 of 6 groups by a factorial design: leaflet or no leaflet and 1 of 3 antibiotic groups (immediate antibiotics, no offer of antibiotics, and delayed antibiotics). INTERVENTION: Three strategies, immediate antibiotics (n = 262), a delayed antibiotic prescription (n = 272), and no offer of antibiotics (n = 273), were prescribed. Approximately half of each group received an information leaflet (129 for immediate antibiotics, 136 for delayed antibiotic prescription, and 140 for no antibiotics). MAIN OUTCOME MEASURES: Symptom duration and severity. RESULTS: A total of 562 patients (70%) returned complete diaries and 78 (10%) provided information about both symptom duration and severity. Cough rated at least "a slight problem" lasted a mean of 11.7 days (25% of patients had a cough lasting > or =17 days). An information leaflet had no effect on the main outcomes. Compared with no offer of antibiotics, other strategies did not alter cough duration (delayed, 0.75 days; 95% confidence intervals [CI], -0.37 to 1.88; immediate, 0.11 days; 95% CI, -1.01 to 1.24) or other primary outcomes. Compared with the immediate antibiotic group, slightly fewer patients in the delayed and control groups used antibiotics (96%, 20%, and 16%, respectively; P<.001), fewer patients were "very satisfied" (86%, 77%, and 72%, respectively; P = .005), and fewer patients believed in the effectiveness of antibiotics (75%, 40%, and 47%, respectively; P<.001). There were lower reattendances within a month with antibiotics (mean attendances for no antibiotics, 0.19; delayed, 0.12; and immediate, 0.11; P = .04) and higher attendance with a leaflet (mean attendances for no leaflet, 0.11; and leaflet, 0.17; P = .02). CONCLUSION: No offer or a delayed offer of antibiotics for acute uncomplicated lower respiratory tract infection is acceptable, associated with little difference in symptom resolution, and is likely to considerably reduce antibiotic use and beliefs in the effectiveness of antibiotics.

Acute Disease↗
PubMed2003

Enhanced dispersibility and deposition of spray-dried powders for pulmonary gene therapy.

Spray-drying represents a viable alternative to freeze-drying for preparing dry powder dispersions for delivering macromolecules to the lung. The dispersibility of spray-dried powders is limited however, and needs to be enhanced to improve lung deposition and subsequent biological activity. In this study, we investigate the utility of leucine as a dry powder dispersibility enhancer when added prior to spray-drying a model non-viral gene therapy formulation (lipid:polycation:pDNA, LPD). Freeze-dried lactose-LPD, spray-dried lactose-LPD and spray-dried leucine-lactose-LPD powders were prepared. Scanning electron microscopy showed that leucine increased the surface roughness of spray-dried lactose particles. Particle size analysis revealed that leucine-containing spray-dried powders were unimodally dispersed with a mean particle diameter of 3.12 microm. Both gel electrophoresis and in vitro cell (A549) transfection showed that leucine may compromise the integrity and biological functionality of the gene therapy vector. The deposition of the leucine containing powder was however significantly enhanced as evidenced by an increase in gene expression mediated by dry powder collected at lower stages of a multistage liquid impinger (MSLI). Further studies are required to determine the potential of leucine as a ubiquitous dispersibility enhancer for a variety of pulmonary formulations.

Cell Line, Tumor↗
PubMed2002

Predictors of poor outcome and benefits from antibiotics in children with acute otitis media: pragmatic randomised trial.

OBJECTIVES: To identify which children with acute otitis media are at risk of poor outcome and to assess benefit from antibiotics in these children. DESIGN: Secondary analysis of randomised controlled trial cohort. SETTING: Primary care. PARTICIPANTS: 315 children aged 6 months to 10 years. INTERVENTION: Immediate or delayed (taken after 72 hours if necessary) antibiotics. MAIN OUTCOME MEASURE: Predictors of short term outcome: an episode of distress or night disturbance three days after child saw doctor. RESULTS: Distress by day three was more likely in children with high temperature (adjusted odds ratio 4.5, 95% confidence interval 2.3 to 9.0), vomiting (2.6,1.3 to 5.0), and cough (2.0, 1.1 to 3.8) on day one. Night disturbance by day three was more likely with high temperature 2.4 (1.2 to 4.8), vomiting (2.1,1.1 to 4.0), cough (2.3,1.3 to 4.2), and ear discharge (2.1, 1.2 to 3.9). Among the children with high temperature or vomiting, distress by day three was less likely with immediate antibiotics (32% for immediate v 53% for delayed, chi2=4.0; P=0.045, number needed to treat 5) as was night disturbance (26% v 59%, chi2=9.3; P=0.002; number needed to treat 3). In children without higher temperature or vomiting, immediate antibiotics made little difference to distress by day three (15% v 19%, chi2=0.74; P=0.39) or night disturbance (20% v 27%, chi2=1.6; P=0.20). Addition of cough did not significantly improve prediction of benefit. CONCLUSION: In children with otitis media but without fever and vomiting antibiotic treatment has little benefit and a poor outcome is unlikely.

Acute Disease↗
PubMed2002

Antibiotic prescribing and admissions with major suppurative complications of respiratory tract infections: a data linkage study.

BACKGROUND: Systematic reviews of antibiotic treatment of common acute respiratory tract infections (RTIs) suggest modest symptomatic benefit, but provide limited evidence that prescribing prevents complications. AIM: To assess the relationship between penicillin prescribing (the most commonly used group of antibiotics for RTIs) and hospital admission with complications. DESIGN OF STUDY: Data linkage study. SETTING: Ninety-six health authorities of England for the year 1997-1998. METHOD: Hospital admissions related to RTIs were linked with prescribing analysis and cost (PACT) data. RESULTS: There was close correlation between items of penicillin use and total antibiotic use (r = 0.96). After controlling for SMR, age, sex, and Townsend score, a one-unit increase in penicillin use (items dispensed per capita) was associated with a reduction in annual incidence per 10,000 of admissions for quinsy (-3.55 admissions, 95% confidence interval [CI] = -6.85 to -0.26), and mastoiditis (square root of incidence of admissions = -1.05, 95% CI = -1.82 to -0.27). This does not represent lower referral thresholds among higher prescribers as higher prescribing was associated with more admissions for tonsillectomy and overall admissions. Increasing prescribing by 2000 items of penicillin for a practice of 10,000 patients could possibly prevent one admission for either mastoiditis or quinsy. CONCLUSION: Higher antibiotic prescribing is associated with significantly fewer admissions with major complications. However, the overall size of the effect is modest and it is difficult to advocate an overall increase in prescribing to prevent complications. Future research should concentrate on finding better methods of targeting antibiotics to individuals at risk of poor outcome.

Acute Disease↗