Drug therapies for reducing gastric acidity in people with cystic fibrosis

Timing of pancreatic enzyme replacement therapy (PERT) in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is an autosomal recessive, life-limiting, multisystem disease affecting over 70,000 individuals worldwide. Between 80% and 90% of people with CF suffer with pancreatic exocrine insufficiency, which if left untreated, leads to a poor nutritional status. Pancreatic enzyme replacement therapy (PERT) has been shown to be effective in improving nutritional status and subsequently associated with improved lung function. However, the timings of PERT administration in relation to a meal are subjective and not standardised, meaning that variations in the timing of PERT dosing persist.

OBJECTIVES

The primary objective of the review is to compare the efficacy (fat absorption) and effectiveness (nutritional status, lung function and quality of life) of different PERT dosing strategies in terms of timing of administration for treating dietary malabsorption in all individuals with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews. Date of last search: 24 June 2021. We also searched ongoing trials registers on 09 July 2021.

SELECTION CRITERIA

Randomised controlled trials (RCTs), including cross-over RCTs with a minimum washout period of two weeks, and quasi-RCTs of PERT dosing regimens in people (of any age) with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed and screened the studies identified from the searches. We planned to use GRADE to assess the certainty of evidence for our pre-specified critical outcomes, but we did not identify any eligible studies.

MAIN RESULTS

No studies met the eligibility criteria and therefore we did not include any in this review. The excluded studies were either cross-over in design (but lacking a sufficient washout period between treatments) or did not assess the timing of PERT. One study which was terminated early is awaiting assessment pending further information.

AUTHORS' CONCLUSIONS

We were unable to determine whether one dosing schedule for PERT is better than another since we identified no eligible RCTs. While the introduction of PERT to people with CF can improve their nutritional status, there are a limited number of studies which address this review question, and none met our eligibility criteria. Since malnutrition and adverse gastrointestinal symptoms remain a common feature in CF, the assessment of the relative performance of dosing schedules may provide evidence to improve outcomes in people with CF who are pancreatic insufficient. Further research is needed to fully evaluate the role of dosing schedules for PERT in fat absorption. Research should also establish reliable outcome measures and minimal clinically important differences. While RCTs with a cross-over design may have advantages over a parallel group design, an adequate washout period between intervention periods is essential.

Use of proton pump inhibitors is associated with lower hemoglobin levels in people with cystic fibrosis

BACKGROUND

Proton pump inhibitors (PPIs) and histamine H2-receptor antagonists (H2RAs) are commonly prescribed to people with cystic fibrosis (PwCF) to treat gastroesophageal reflux disease (GERD) and/or protect pancreatic enzymes from degradation in the stomach. Acid suppressive medications (ASMs) could theoretically reduce hemoglobin (Hgb) levels by restricting enteral iron absorption, but evidence of an association between use of ASMs and lower Hgb levels is lacking in PwCF.

METHODS

We used unadjusted and covariate-adjusted generalized linear mixed models (GLMMs) to estimate the fixed effects of using versus never using ASMs on annual Hgb levels of PwCF in the U.S. Cystic Fibrosis Foundation Patient Registry (CFFPR) from 2011 to 2017.

RESULTS

There were 9850 users and 9007 never-users of ASMs from 2011 to 2017 who met inclusion criteria. Not adjusting for covariates, Hgb estimates were lower for male and female H2RA and/or PPI users versus never-users. Adjusting for covariates, mean Hgb was 0.1 g/dl (95% CI: 0.03, 0.17) lower for males that exclusively used PPIs than it was for male never-users of ASMs (p = .008). Adjusting for covariates, mean Hgb levels were 0.11 g/dl (95% CI: 0.04, 0.18) lower for females that exclusively used PPIs and 0.16 g/dl (95% CI: 0.05, 0.27) lower for females that used PPIs and H2RAs concurrently than it was for female never-users of ASMs (p = .005 and p = .002 for respective comparisons).

CONCLUSIONS

Males and females with cystic fibrosis (CF) who used PPIs and females with CF who concurrently used PPIs and H2RAs had lower Hgb levels than never-users of ASMs of the same sex in the CFFPR from 2011 to 2017.

Improved residual fat malabsorption and growth in children with cystic fibrosis treated with a novel oral structured lipid supplement: A randomized controlled trial

Background

In the primary analysis of a 12-month double-blind randomized active placebo-controlled trial, treatment of children with cystic fibrosis (CF) and pancreatic insufficiency (PI) with a readily absorbable structured lipid (Encala™, Envara Health, Wayne, PA) was safe, well-tolerated and improved dietary fat absorption (stool coefficient of fat absorption [CFA]), growth, and plasma fatty acids (FA).

Objective

To determine if the Encala™ treatment effect varied by severity of baseline fat malabsorption.

Methods

Subjects (n = 66, 10.5±3.0 yrs, 39% female) with baseline CFA who completed a three-month treatment with Encala™ or a calorie and macronutrient-matched placebo were included in this subgroup analysis. Subjects were categorized by median baseline CFA: low CFA (<88%) and high CFA (≥88%). At baseline and 3-month evaluations, CFA (72-hour stool, weighed food record) and height (HAZ), weight (WAZ) and BMI (BMIZ) Z-scores were calculated. Fasting plasma fatty acid (FA) concentrations were also measured.

Results

Subjects in the low CFA subgroup had significantly improved CFA (+7.5±7.2%, mean 86.3±6.7, p = 0.002), and reduced stool fat loss (-5.7±7.2 g/24 hours) following three months of Encala^TM treatment. These subjects also had increased plasma linoleic acid (+20%), α-linolenic acid (+56%), and total FA (+20%) (p≤0.005 for all) concentrations and improvements in HAZ (0.06±0.08), WAZ (0.17±0.16), and BMIZ (0.20±0.25) (p≤0.002 for all). CFA and FA were unchanged with placebo in the low CFA group, with some WAZ increases (0.14±0.24, p = 0.02). High CFA subjects (both placebo and Encala™ groups) had improvements in WAZ and some FA.

Conclusions

Subjects with CF, PI and more severe fat malabsorption experienced greater improvements in CFA, FA and growth after three months of Encala™ treatment. Encala™ was safe, well-tolerated and efficacious in patients with CF and PI with residual fat malabsorption and improved dietary energy absorption, weight gain and FA status in this at-risk group.

Challenges in the management of pancreatic exocrine insufficiency

Pancreatic exocrine insufficiency (PEI) occurs when the insufficient secretion or function of pancreatic enzymes leads to maldigestion, most commonly as a result of chronic pancreatitis and pancreatic cancer. The condition is associated with significant morbidity and reductions in quality of life, even in milder forms. The challenges in approaching this condition include the non-specific presentation of mild to moderate PEI, and the lack of a convenient, accurate diagnostic test in this cohort. Classical symptoms appear late in the disease, and the diagnosis should be considered before steatorrhoea develops. Direct pancreatic function tests are the reference standard for diagnosis, but are invasive and not widely available. The faecal elastase-1 (FE-1) stool test is widely available and has been shown to be as effective as the 13C-mixed triglyceride breath test in more advanced disease. We recommend a pragmatic diagnostic approach that combines clinical history, assessment of nutritional status and measurement of FE-1. The critical first step is to consider the diagnosis. Once the diagnosis is confirmed, pancreatic enzyme replacement therapy should be initiated. The variety of enzyme preparations and recommended dosing regimens can present a challenge when selecting an adequate initial dose. Non-response should be actively sought and addressed in a systematic manner. This article discusses these challenges, and presents a practical approach to the diagnosis and management of PEI.