Efficacy of cryotherapy as first line therapy in patients with Barrett's neoplasia: a systematic review and pooled analysis

Cryotherapy has been used as salvage therapy; however, its efficacy as first line treatment in patients with Barrett's esophagus (BE) neoplasia has not been well studied. The aim of this paper was to perform a systematic review to look at the efficacy of cryotherapy as the primary treatment of BE. An electronic database search was performed (PubMed, Embase, Cochrane, and Google Scholar) to search for studies with cryotherapy as the initial primary modality of ablation in patients with BE neoplasia. Studies that included patients with other prior forms of therapy were excluded. The primary outcomes were the pooled rates of complete eradication of intestinal metaplasia (CE-IM) and CE of neoplasia (CE-N). Secondary outcomes were recurrence rates of neoplasia and intestinal metaplasia (IM) and adverse events. The statistical software OpenMetaAnalyst was used for analysis with pooled estimates reported as proportions (%) with 95% confidence intervals (CI) with heterogeneity (I2) among studies. The search revealed 6 eligible studies with a total of 282 patients (91.5% male, average age 65.3 years) with 459 person years of follow-up. 69.35% [95% CI (52.1%-86.5%)] of patients achieved CE-IM and 97.9% (95% CI: 95.5%-100%) had CE-N. 7.3% of patients had persistent dysplasia with 4% progressing to cancer. The recurrence rate of neoplasia was 10.4 and that of IM was 19.1 per 100 patient years of follow-up. The overall rate of stricture formation was 4.9%. There are scarce data on the use of cryotherapy as the primary modality for the treatment of BE dysplasia. The published data demonstrate efficacy rates of 69% and 98% for complete eradication of metaplasia and neoplasia, respectively. These results need to be assessed in prospective, comparative trials with other forms of therapy.

Changes in symptom reflux association using dynamic pH thresholds during ambulatory pH monitoring: an observational cross-sectional study

Symptom reflux association (SRA) assesses symptoms associated with reflux events defined by pH <4.0, but limited symptoms associate with reflux events. We evaluated the impact of alternate pH thresholds on SRA in a large ambulatory pH database. Acid exposure time (AET), reflux events, and associated symptoms (within 2 minutes following a reflux event) were extracted from ambulatory pH studies performed off antireflux therapy (722 patients, 49.1 ± 0.5 years, 66.8% F) over a 7-year period. Symptom association probability (SAP) and symptom index (SI) were calculated at pH 3.5, 4.0, 4.5, and 5. Receiver operating characteristics (ROC) were generated using SRA at any pH as gold standard; areas under the curve (AUCs) were determined. Discordant cases were reanalyzed to determine changes in SRA and predictors of change using multivariate regression. At pH 4.0, 41% had a positive SAP, and 34% had a positive SI. While there was sustained gain in SI positivity from acidic to more weakly acidic pH thresholds, SAP positivity was highest at pH 4.5. On ROC analysis, performance characteristics were best at pH 4.0 (AUC 0.97) for SAP, and at pH 4.5 and 5.0 (AUC 0.92-0.94) for SI. On multivariate logistic regression adjusting for age, gender, and change in AET and reflux events, only number of associated symptoms predicted change in SRA (P < 0.0001). Changing pH thresholds for reflux events augments SRA by increasing reflux events associated with existing symptoms, while symptom recording remains the principal determinant of SRA.

Enhanced beta cell proliferation in mice overexpressing a constitutively active form of Akt and one allele of p21Cip

AIMS/HYPOTHESIS

The ability of pancreatic beta cells to proliferate is critical both for normal tissue maintenance and in conditions where there is an increased demand for insulin. Protein kinase B(Akt) plays a major role in promoting proliferation in many cell types, including the insulin-producing beta cells. We have previously reported that mice overexpressing a constitutively active form of Akt(caAkt (Tg)) show enhanced beta cell proliferation that is associated with increased protein levels of cyclin D1, cyclin D2 and cyclin-dependent kinase inhibitor 1A (p21(Cip)). In the present study, we sought to assess the mechanisms responsible for augmented p21(Cip) levels in caAkt(Tg) mice and test the role of p21(Cip) in the proliferative responses induced by activation of Akt signalling.

METHODS

To gain a greater understanding of the relationship between Akt and p21(Cip), we evaluated the mechanisms involved in the modulation of p2(Cip) by Akt and the in vivo role of reduced p21(Cip) in proliferative responses induced by Akt.

RESULTS

Our experiments showed that Akt signalling regulates p21(Cip) transcription and protein stability. caAkt(Tg) /p21(Cip+/-) mice exhibited fasting and fed hypoglycaemia as well as hyperinsulinaemia when compared with caAkt(Tg) mice. Glucose tolerance tests revealed improved glucose tolerance in caAkt(Tg)/p21(Cip+/-) mice compared with caAkt (Tg). These changes resulted from increased proliferation, survival and beta cell mass in caAkt(Tg)/p21(Cip+/-) compared with caAkt(Tg) mice.

CONCLUSIONS/INTERPRETATION

Our data indicate that increased p21(Cip) levels in caAkt(Tg) mice act as a compensatory brake, protecting beta cells from unrestrained proliferation. These studies imply that p21(Cip) could play important roles in the adaptive responses of beta cells to proliferate in conditions such as in insulin resistance.

Assessment of concordance of symptom reflux association tests in ambulatory pH monitoring

BACKGROUND

Both simple proportions and statistical tests are utilised for symptom-reflux association. We systematically compared three such tests in a clinical setting.

AIM

To compare the three commonly used symptom reflux association tests in a large cohort of patients undergoing ambulatory pH monitoring for the evaluation of oesophageal symptoms.

METHODS

Ambulatory pH data from 772 symptomatic subjects (49.1 ± 0.5 years; 479 F) tested off therapy were assessed for acid exposure time (AET, elevated when pH <4 for ≥4%), symptom index (SI, ≥50% when positive), and symptom association probability (SAP) and Ghillebert probability estimate (GPE, P < 0.05 when positive). Test concordance and discordance were individually assessed; discordance between statistical tests was minor if one had P < 0.1 while the other was positive. Logistic regression determined independent predictors of test discordance.

RESULTS

The SAP, GPE and SI were positive in 42.7%, 39.3% and 33.9% respectively. GPE performed extremely well compared to SAP (sensitivity 0.95, specificity 0.91), with major discordance in only 2.8%. Positive concordance was significantly higher when AET was abnormal. GPE underestimated symptom association compared to SAP, whereas SAP was subject to symptom over-counting in 33.3% of discordant cases. GPE-SAP discordance was associated with higher AET (7.5% vs. 5.1%) and more symptoms (19.3 vs. 10.7, P > 0.001 for each comparison with concordant tests); both remained significant on logistic regression analysis (P ≤ 0.003). SI was discordant with SAP when symptoms were extremely frequent (median 19, IQR 10-32) or limited (median 1, IQR 1-2), and concordant when median 6 symptoms (IQR 3-12) were recorded.

CONCLUSIONS

The GPE can be used interchangeably with SAP in symptom reflux association. SI has uncertain value with very high and very low symptom counts.

Assessment of concordance of symptom reflux association tests in ambulatory pH monitoring

BACKGROUND

Both simple proportions and statistical tests are utilised for symptom-reflux association. We systematically compared three such tests in a clinical setting.

AIM

To compare the three commonly used symptom reflux association tests in a large cohort of patients undergoing ambulatory pH monitoring for the evaluation of oesophageal symptoms.

METHODS

Ambulatory pH data from 772 symptomatic subjects (49.1 ± 0.5 years; 479 F) tested off therapy were assessed for acid exposure time (AET, elevated when pH <4 for ≥4%), symptom index (SI, ≥50% when positive), and symptom association probability (SAP) and Ghillebert probability estimate (GPE, P < 0.05 when positive). Test concordance and discordance were individually assessed; discordance between statistical tests was minor if one had P < 0.1 while the other was positive. Logistic regression determined independent predictors of test discordance.

RESULTS

The SAP, GPE and SI were positive in 42.7%, 39.3% and 33.9% respectively. GPE performed extremely well compared to SAP (sensitivity 0.95, specificity 0.91), with major discordance in only 2.8%. Positive concordance was significantly higher when AET was abnormal. GPE underestimated symptom association compared to SAP, whereas SAP was subject to symptom over-counting in 33.3% of discordant cases. GPE-SAP discordance was associated with higher AET (7.5% vs. 5.1%) and more symptoms (19.3 vs. 10.7, P > 0.001 for each comparison with concordant tests); both remained significant on logistic regression analysis (P ≤ 0.003). SI was discordant with SAP when symptoms were extremely frequent (median 19, IQR 10-32) or limited (median 1, IQR 1-2), and concordant when median 6 symptoms (IQR 3-12) were recorded.

CONCLUSIONS

The GPE can be used interchangeably with SAP in symptom reflux association. SI has uncertain value with very high and very low symptom counts.