Colonoscopy preparation: are our patients at risk?

The modern bowel preparation in colonoscopy

Adequate bowel preparation is essential for optimal colonoscopy. Suboptimal bowel preparation occurs in 25% to 40% of cases and is associated with canceled procedures, prolonged procedure time, incomplete examination, increased cost, and missed pathology. There are several effective formulations for colon cleansing with a good safety profile. Split dosing should be implemented whenever possible in an effort to enhance tolerance and adherence, and improve mucosal visibility and overall quality of the examination. In this review, modern bowel preparations are discussed including their mechanism of action, mode of use, safety, and how to optimize outcomes.

Intermediate bioelectrolyte changes after phospho-soda or polyethylene glycol precolonoscopic laxatives in a population undergoing health examinations

BACKGROUND

Colonoscopy is a common procedure for diagnosing and screening colon cancer and other bowel-related diseases. Many studies have pointed out that using phospho-soda as a bowel preparation can cause obvious electrolyte abnormalities or acute kidney injury. Nonetheless, there are few studies related to its prevalence and risk factors in the population undergoing health examinations. Our aim was to compare the biochemical and electrolyte changes after using two commonly used bowel preparation regimens in this population.

METHODS

In this retrospective study, we collected data about participants who, before a screening colonoscopy, used oral phospho-soda laxatives in 2006, and those who used polyethylene glycol-based laxatives in 2005. Several serum biochemical and electrolyte profiles were compared between the two groups. Additional risk factors of hyperphosphatemia, a well-known side effect of phospho-soda, were also derived.

RESULTS

We enrolled a total of 2270 participants (1321 in 2005; 1449 in 2006). The basic demographic data of the two groups were not statistically different. Nonetheless, between the two groups, some serum biochemical and electrolytic data differed significantly: in those using oral phospho-soda laxatives, we found a higher prevalence of hyperuricemia, hypocalcemia, hypokalemia, hypernatremia and hyperphosphatemia. Further analyses showed that using oral phospho-soda laxatives was a risk factor for hyperphosphatemia; conversely, being male was a protective factor.

CONCLUSION

Oral phospho-soda laxatives indeed influence the biochemical and electrolyte profiles of persons undergoing health examinations. One should be careful when interpreting bioelectrolytic data while using phospho-soda as a bowel preparation.

A population-based case-crossover study of polyethylene glycol use and acute renal failure risk in the elderly

AIM: To evaluate the possibility of an association between polyethylene glycol (PEG) and acute renal failure (ARF) in elderly patients using a health insurance claims database.

METHODS: We conducted a population-based case-crossover study using information obtained from Korean Health Insurance Review and Assessment Service (HIRA) claims from January 1, 2005 to December 31, 2005 (Seoul, Korea). The study population consisted of elderly patients who received PEG prior to experiencing their first ARF-related hospitalization from April 1, 2005 to December 31, 2005. For each patient, one case and two control periods were matched. PEG use in a 2- or 4-wk window period prior to hospitalization for ARF was compared with PEG use in two earlier 2- or 4-wk control window periods. Conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95% CI, adjusting for concomitant uses of diuretics, angiotensin converting enzyme inhibitors, non-steroidal anti-inflammatory drugs, antibiotics, anti-cancer drugs, and contrast media.

RESULTS: Within the HIRA database which contained 1 093 262 elderly patients, 1156 hospitalized ARF cases were identified. Among these cases, PEG was prescribed to 17 (1.5%) patients before hospitalization. The adjusted ORs when applying the 2- and 4-wk window periods were 0.4 (95% CI: 0.03-5.24) and 2.1 (95% CI: 0.16-27.78), respectively.

CONCLUSION: No increased risk of ARF was found in elderly PEG users. However, based on the limited number of study subjects, further analysis should be performed to confirm these results.

Risk of further decline in renal function after the use of oral sodium phosphate or polyethylene glycol in patients with a preexisting glomerular filtration rate below 60 ml/min

OBJECTIVES

The aim of this study was to estimate the risk of further creatinine increase in patients with preexisting renal disease after the use of oral sodium phosphate (OSP) versus polyethylene glycol (PEG), and to study usage patterns of OSP in relation to renal function.

METHODS

A cohort study was done using clinical records and electronic patient information from the Henry Ford Health System (HFHS) in patients who had used either OSP or PEG for colonoscopy between February 1999 and April 2006. Among patients with an estimated GFR < 60 ml/min before colonoscopy, we identified cases with an unexplained creatinine increase of > or = 0.5 mg/dl within 14 days after colonoscopy.

RESULTS

We identified 7,971 OSP and 1,511 PEG users. Relative use of OSP versus PEG decreased from 88.0% before 2004 to 48.4% in 2006. 70.2% of OSP users had no recorded creatinine determination within 60 days before colonoscopy, and this proportion did not decrease over time. The study population included 317 patients with a baseline GFR < 60 ml/min, and we identified one case with an unexplained creatinine increase > or = 0.5 mg/dl among 191 PEG users (0.5%) versus eight cases among 126 OSP users (6.3%). Unadjusted and adjusted relative risk estimates on comparing OSP with PEG were 12.1 (95% CI, 1.5-95.8) and 12.6 (95% CI, 1.5-106.5), respectively.

CONCLUSIONS

In patients with preexisting renal disease, OSP use was associated with an increased risk of aggravated renal dysfunction versus PEG. Creatinine measurement with GFR estimation should be done before OSP administration in order to avoid its use in patients with renal disease.