The advantage of using the between approach to set targets and monitor progress is that it mirrors the long used and familiar health inequality measure of the standardised mortality ratio. However, we join Shaw et al in questioning whether this conventional approach is fit for purpose.Most descriptions of the national inequality targets do not specify whether the reductions required are relative or absolute, as if it does not matter. We have shown why it does matter. Moreover, lack of transparency in this regard has led to the inconsistent use of relative and absolute gaps in government targets going unquestioned. It has also resulted in confusion over how to establish local health improvement targets that are consistent with national policy on reducing health inequalities. Research methods Reporting attrition in randomised controlled trialsJo C Dumville, David J Torgerson, Catherine E Hewitt Loss to follow-up can greatly affect the strength of a trial's findings. But most reports do not give readers enough information for them to be able to understand the potential effects

A comprehensive review of current evidence found some evidence that preoperative skin preparation with 0.5% chlorhexidine in methylated spirits was associated with lower rates of SSIs following clean surgery than alcohol-based povidone iodine paint. However this single study was poorly reported. Practitioners may therefore elect to consider other characteristics such as costs and potential side effects when choosing between alternatives.The design of future trials should be driven by the questions of high priority to decision makers. It may be that investment in at least one large trial (in terms of participants) is warranted in order to add definitive and hopefully conclusive data to the current evidence base. Ideally any future trial would evaluate the iodine-containing and chlorhexidine-containing solutions relevant to current practice as well as the type of solution used (alcohol vs. aqueous).

Background Indications for the use of negative pressure wound therapy (NPWT) are broad and include prophylaxis for surgical site infections (SSIs). While existing evidence for the effectiveness of NPWT remains uncertain, new trials necessitated an updated review of the evidence for the effects of NPWT on postoperative wounds healing by primary closure. Objectives To assess the effects of negative pressure wound therapy for preventing surgical site infection in wounds healing through primary closure. Search methods We searched the Cochrane Wounds Specialised Register, CENTRAL, Ovid MEDLINE (including In-Process & Other Non-Indexed Citations), Ovid Embase, and EBSCO CINAHL Plus in February 2018. We also searched clinical trials registries for ongoing and unpublished studies, and checked reference lists of relevant included studies as well as reviews, meta-analyses, and health technology reports to identify additional studies. There were no restrictions on language, publication date, or setting. Selection criteria We included trials if they allocated participants to treatment randomly and compared NPWT with any other type of wound dressing, or compared one type of NPWT with another type of NPWT. Data collection and analysis Four review authors independently assessed trials using predetermined inclusion criteria. We carried out data extraction, 'Risk of bias' assessment using the Cochrane 'Risk of bias' tool, and quality assessment according to GRADE methodology.

Background Pressure ulcers (i.e. bedsores, pressure sores, decubitus ulcers) are areas of localised damage to the skin and underlying tissue. They are common in the elderly and immobile, and costly in financial and human terms. Pressure-relieving support surfaces (i.e. beds, mattresses, seat cushions etc) are used to help prevent ulcer development. Objectives This systematic review seeks to establish: (1) the extent to which pressure-relieving support surfaces reduce the incidence of pressure ulcers compared with standard support surfaces, and, (2) their comparative effectiveness in ulcer prevention.

Background During the COVID-19 pandemic, there have been concerns regarding potential bias in pulse oximetry measurements for people with high levels of skin pigmentation. We systematically reviewed the effects of skin pigmentation on the accuracy of oxygen saturation measurement by pulse oximetry (SpO2) compared with the gold standard SaO2 measured by CO-oximetry. Methods We searched Ovid MEDLINE, Ovid Embase, EBSCO CINAHL, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform (up to December 2021) for studies with SpO2–SaO2 comparisons and measuring the impact of skin pigmentation or ethnicity on pulse oximetry accuracy. We performed meta-analyses for mean bias (the primary outcome in this review) and its standard deviations (SDs) across studies included for each subgroup of skin pigmentation and ethnicity and used these pooled mean biases and SDs to calculate accuracy root-mean-square (Arms) and 95% limits of agreement. The review was registered with the Open Science Framework (https://osf.io/gm7ty). Results We included 32 studies (6505 participants): 15 measured skin pigmentation and 22 referred to ethnicity. Compared with standard SaO2 measurement, pulse oximetry probably overestimates oxygen saturation in people with the high level of skin pigmentation (pooled mean bias 1.11%; 95% confidence interval 0.29 to 1.93%) and people described as Black/African American (1.52%; 0.95 to 2.09%) (moderate- and low-certainty evidence). The bias of pulse oximetry measurements for people with other levels of skin pigmentation or those from other ethnic groups is either more uncertain or suggests no overestimation. Whilst the extent of mean bias is small or negligible for all subgroups evaluated, the associated imprecision is unacceptably large (pooled SDs > 1%). When the extent of measurement bias and precision is considered jointly, pulse oximetry measurements for all the subgroups appear acceptably accurate (with Arms < 4%). Conclusions Pulse oximetry may overestimate oxygen saturation in people with high levels of skin pigmentation and people whose ethnicity is reported as Black/African American, compared with SaO2. The extent of overestimation may be small in hospital settings but unknown in community settings. Review protocol registration https://osf.io/gm7ty

Background Indications for the use of negative pressure wound therapy (NPWT) are broad and include prophylaxis for surgical site infections (SSIs). Existing evidence for the effectiveness of NPWT on postoperative wounds healing by primary closure remains uncertain. Objectives To assess the effects of NPWT for preventing SSI in wounds healing through primary closure, and to assess the cost‐effectiveness of NPWT in wounds healing through primary closure. Search methods In January 2021, we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In‐Process & Other Non‐Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries and references of included studies, systematic reviews and health technology reports. There were no restrictions on language, publication date or study setting. Selection criteria We included trials if they allocated participants to treatment randomly and compared NPWT with any other type of wound dressing, or compared one type of NPWT with another. Data collection and analysis At least two review authors independently assessed trials using predetermined inclusion criteria. We carried out data extraction, assessment using the Cochrane risk of bias tool, and quality assessment according to Grading of Recommendations, Assessment, Development and Evaluations methodology. Our primary outcomes were SSI, mortality, and wound dehiscence. Main results In this fourth update, we added 18 new randomised controlled trials (RCTs) and one new economic study, resulting in a total of 62 RCTs (13,340 included participants) and six economic studies. Studies evaluated NPWT in a wide range of surgeries, including orthopaedic, obstetric, vascular and general procedures. All studies compared NPWT with standard dressings. Most studies had unclear or high risk of bias for at least one key domain. Primary outcomes Eleven studies (6384 participants) which reported mortality were pooled. There is low‐certainty evidence showing there may be a reduced risk of death after surgery for people treated with NPWT (0.84%) compared with standard dressings (1.17%) but there is uncertainty around this as confidence intervals include risk of benefits and harm; risk ratio (RR) 0.78 (95% CI 0.47 to 1.30; I 2 = 0%). Fifty‐four studies reported SSI; 44 studies (11,403 participants) were pooled. There is moderate‐certainty evidence that NPWT probably results in fewer SSIs (8.7% of participants) than treatment with standard dressings (11.75%) after surgery; RR 0.73 (95% CI 0.63 to 0.85; I 2 = 29%). Thirty studies reported wound dehiscence; 23 studies (8724 participants) were pooled. There is moderate‐certainty evidence that there is probably little or no differe...

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Background and Purpose-Conventional methods of assessing cerebrovascular reactivity (CVR) omit the influence of blood pressure (BP). This study demonstrates the significant influence of BP during the assessment of CVR in patients with carotid artery disease. Methods-In 56 subjects the CVR was bilaterally assessed by measurement of cerebral blood flow velocity change in response to inhalation of 5% CO 2 in air while BP was continuously monitored. Three methods of calculating the CVR were used: the conventional ratio between relative cerebral blood flow velocity and end-tidal CO 2 , simple linear regression, and multiple linear regression analysis (MLRA). The clinical significance of the difference in CVR indices was evaluated. The Bland-Altman test was applied to quantify the comparability and bias between measurements. The magnitude and significance of a change in BP during the CVR assessment were calculated in conjunction with an estimate of the velocity change attributed to the BP. The statistical significance of the data segment length on the variability and magnitude of the CVR index was computed. Results-The value of the CVR index was reduced by 20% and 6% in comparison to the conventional ratio approach when MLRA and linear regression were applied, respectively. With the use of MLRA, in 96% of cases the value of the BP coefficient was statistically significant, and in four patients the increase in velocity was primarily attributed to the increase in BP. Conclusions-The influence of BP is significant and requires consideration when the CVR index is calculated in patients with carotid artery disease. (Stroke. 1998;29:968-974.)