Semantic Speech Networks Linked to Formal Thought Disorder in Early Psychosis

BACKGROUND AND HYPOTHESIS

Mapping a patient's speech as a network has proved to be a useful way of understanding formal thought disorder in psychosis. However, to date, graph theory tools have not explicitly modelled the semantic content of speech, which is altered in psychosis.

STUDY DESIGN

We developed an algorithm, "netts," to map the semantic content of speech as a network, then applied netts to construct semantic speech networks for a general population sample (N = 436), and a clinical sample comprising patients with first episode psychosis (FEP), people at clinical high risk of psychosis (CHR-P), and healthy controls (total N = 53).

STUDY RESULTS

Semantic speech networks from the general population were more connected than size-matched randomized networks, with fewer and larger connected components, reflecting the nonrandom nature of speech. Networks from FEP patients were smaller than from healthy participants, for a picture description task but not a story recall task. For the former task, FEP networks were also more fragmented than those from controls; showing more connected components, which tended to include fewer nodes on average. CHR-P networks showed fragmentation values in-between FEP patients and controls. A clustering analysis suggested that semantic speech networks captured novel signals not already described by existing NLP measures. Network features were also related to negative symptom scores and scores on the Thought and Language Index, although these relationships did not survive correcting for multiple comparisons.

CONCLUSIONS

Overall, these data suggest that semantic networks can enable deeper phenotyping of formal thought disorder in psychosis. Whilst here we focus on network fragmentation, the semantic speech networks created by Netts also contain other, rich information which could be extracted to shed further light on formal thought disorder. We are releasing Netts as an open Python package alongside this manuscript.

Colonoscopy surveillance following adenoma removal to reduce the risk of colorectal cancer: a retrospective cohort study

BACKGROUND

Colonoscopy surveillance is recommended for some patients post polypectomy. The 2002 UK surveillance guidelines classify post-polypectomy patients into low, intermediate and high risk, and recommend different strategies for each classification. Limited evidence supports these guidelines.

OBJECTIVES

To examine, for each risk group, long-term colorectal cancer incidence by baseline characteristics and the number of surveillance visits; the effects of interval length on detection rates of advanced adenomas and colorectal cancer at first surveillance; and the cost-effectiveness of surveillance compared with no surveillance.

DESIGN

A retrospective cohort study and economic evaluation.

SETTING

Seventeen NHS hospitals.

PARTICIPANTS

Patients with a colonoscopy and at least one adenoma at baseline.

MAIN OUTCOME MEASURES

Long-term colorectal cancer incidence after baseline and detection rates of advanced adenomas and colorectal cancer at first surveillance.

DATA SOURCES

Hospital databases, NHS Digital, the Office for National Statistics, National Services Scotland and Public Health England.

METHODS

Cox regression was used to compare colorectal cancer incidence in the presence and absence of surveillance and to identify colorectal cancer risk factors. Risk factors were used to stratify risk groups into higher- and lower-risk subgroups. We examined detection rates of advanced adenomas and colorectal cancer at first surveillance by interval length. Cost-effectiveness of surveillance compared with no surveillance was evaluated in terms of incremental costs per colorectal cancer prevented and per quality-adjusted life-year gained.

RESULTS

Our study included 28,972 patients, of whom 14,401 (50%), 11,852 (41%) and 2719 (9%) were classed as low, intermediate and high risk, respectively. The median follow-up time was 9.3 years. Colorectal cancer incidence was 140, 221 and 366 per 100,000 person-years among low-, intermediate- and high-risk patients, respectively. Attendance at one surveillance visit was associated with reduced colorectal cancer incidence among low-, intermediate- and high-risk patients [hazard ratios were 0.56 (95% confidence interval 0.39 to 0.80), 0.59 (95% confidence interval 0.43 to 0.81) and 0.49 (95% confidence interval 0.29 to 0.82), respectively]. Compared with the general population, colorectal cancer incidence without surveillance was similar among low-risk patients and higher among high-risk patients [standardised incidence ratios were 0.86 (95% confidence interval 0.73 to 1.02) and 1.91 (95% confidence interval 1.39 to 2.56), respectively]. For intermediate-risk patients, standardised incidence ratios differed for the lower- (0.70, 95% confidence interval 0.48 to 0.99) and higher-risk (1.46, 95% confidence interval 1.19 to 1.78) subgroups. In each risk group, incremental costs per colorectal cancer prevented and per quality-adjusted life-year gained with surveillance were lower for the higher-risk subgroup than for the lower-risk subgroup. Incremental costs per quality-adjusted life-year gained were lowest for the higher-risk subgroup of high-risk patients at £7821.

LIMITATIONS

The observational design means that we cannot assume that surveillance caused the reductions in cancer incidence. The fact that some cancer staging data were missing places uncertainty on our cost-effectiveness estimates.

CONCLUSIONS

Surveillance was associated with reduced colorectal cancer incidence in all risk groups. However, in low-risk patients and the lower-risk subgroup of intermediate-risk patients, colorectal cancer incidence was no higher than in the general population without surveillance, indicating that surveillance might not be necessary. Surveillance was most cost-effective for the higher-risk subgroup of high-risk patients.

FUTURE WORK

Studies should examine the clinical effectiveness and cost-effectiveness of post-polypectomy surveillance without prior classification of patients into risk groups.

TRIAL REGISTRATION

This trial is registered as ISRCTN15213649.

FUNDING

This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 26. See the NIHR Journals Library website for further project information.

Post-polypectomy surveillance interval and advanced neoplasia detection rates: a multicenter, retrospective cohort study

BACKGROUND

Longer post-polypectomy surveillance intervals are associated with increased colorectal neoplasia detection at surveillance in some studies. We investigated this association to inform optimal surveillance intervals.

METHODS

Patients who underwent colonoscopy and post-polypectomy surveillance at 17 UK hospitals were classified as low/high risk by baseline findings. We compared detection rates of advanced adenomas (≥ 10 mm, tubulovillous/villous, high grade dysplasia), high risk findings (HRFs: ≥ 2 serrated polyps/[adenomas] of which ≥ 1 is ≥ 10 mm or has [high grade] dysplasia; ≥ 5 serrated polyps/adenomas; or ≥ 1 nonpedunculated polyp ≥ 20 mm), or colorectal cancer (CRC) at surveillance colonoscopy by surveillance interval (< 18 months, 2, 3, 4, 5, 6 years). Risk ratios (RRs) were estimated using multivariable regression.

RESULTS

Of 11 214 patients, 7216 (64 %) were low risk and 3998 (36 %) were high risk. Among low risk patients, advanced adenoma, HRF, and CRC detection rates at first surveillance were 7.8 %, 3.7 %, and 1.1 %, respectively. Advanced adenoma detection increased with increasing surveillance interval, reaching 9.8 % with a 6-year interval (P trend < 0.001). Among high risk patients, advanced adenoma, HRF, and CRC detection rates at first surveillance were 15.3 %, 10.0 %, and 1.5 %, respectively. Advanced adenoma and CRC detection rates (P trends < 0.001) increased with increasing surveillance interval; RRs (95 % confidence intervals) for CRC were 1.54 (0.68-3.48), 4.44 (1.95-10.08), and 5.80 (2.51-13.40) with 3-, 4-, and 5-year intervals, respectively, versus an interval of < 18 months.

CONCLUSIONS

Metachronous neoplasia was uncommon among low risk patients, even with long surveillance intervals, supporting recommendations for no surveillance in these patients. For high risk patients, a 3-year surveillance interval would ensure timely CRC detection.

Colorectal cancer risk following polypectomy in a multicentre, retrospective, cohort study: an evaluation of the 2020 UK post-polypectomy surveillance guidelines

OBJECTIVE

Colonoscopy surveillance aims to reduce colorectal cancer (CRC) incidence after polypectomy. The 2020 UK guidelines recommend surveillance at 3 years for 'high-risk' patients with ≥2 premalignant polyps (PMPs), of which ≥1 is 'advanced' (serrated polyp (or adenoma) ≥10 mm or with (high-grade) dysplasia); ≥5 PMPs; or ≥1 non-pedunculated polyp ≥20 mm; 'low-risk' patients without these findings are instead encouraged to participate in population-based CRC screening. We examined the appropriateness of these risk classification criteria and recommendations.

DESIGN

Retrospective analysis of patients who underwent colonoscopy and polypectomy mostly between 2000 and 2010 at 17 UK hospitals, followed-up through 2017. We examined CRC incidence by baseline characteristics, risk group and number of surveillance visits using Cox regression, and compared incidence with that in the general population using standardised incidence ratios (SIRs).

RESULTS

Among 21 318 patients, 368 CRCs occurred during follow-up (median: 10.1 years). Baseline CRC risk factors included age ≥55 years, ≥2 PMPs, adenomas with tubulovillous/villous/unknown histology or high-grade dysplasia, proximal polyps and a baseline visit spanning 2-90 days. Compared with the general population, CRC incidence without surveillance was higher among those with adenomas with high-grade dysplasia (SIR 1.74, 95% CI 1.21 to 2.42) or ≥2 PMPs, of which ≥1 was advanced (1.39, 1.09 to 1.75). For low-risk (71%) and high-risk (29%) patients, SIRs without surveillance were 0.75 (95% CI 0.63 to 0.88) and 1.30 (1.03 to 1.62), respectively; for high-risk patients after first surveillance, the SIR was 1.22 (0.91 to 1.60).

CONCLUSION

These guidelines accurately classify post-polypectomy patients into those at high risk, for whom one surveillance colonoscopy appears appropriate, and those at low risk who can be managed by non-invasive screening.

Heterogeneity in colorectal cancer incidence among people recommended 3-yearly surveillance post-polypectomy: a validation study

BACKGROUND

 Colonoscopy surveillance is recommended for patients at increased risk of colorectal cancer (CRC) following adenoma removal. Low-, intermediate-, and high-risk groups are defined by baseline adenoma characteristics. We previously examined intermediate-risk patients from hospital data and identified a higher-risk subgroup who benefited from surveillance and a lower-risk subgroup who may not require surveillance. This study explored whether these findings apply in individuals undergoing CRC screening.

METHODS

 This retrospective study used data from the UK Flexible Sigmoidoscopy Screening Trial (UKFSST), English CRC screening pilot (ECP), and US Kaiser Permanente CRC prevention program (KPCP). Screening participants (50 - 74 years) classified as intermediate-risk at baseline colonoscopy were included. CRC data were available through 2006 (KPCP) or 2014 (UKFSST, ECP). Lower- and higher-risk subgroups were defined using our previously identified baseline risk factors: higher-risk participants had incomplete colonoscopies, poor bowel preparation, adenomas ≥ 20 mm or with high-grade dysplasia, or proximal polyps. We compared CRC incidence in these subgroups and in the presence vs. absence of surveillance using Cox regression.

RESULTS

 Of 2291 intermediate-risk participants, 45 % were classified as higher risk. Median follow-up was 11.8 years. CRC incidence was higher in the higher-risk than lower-risk subgroup (hazard ratio [HR] 2.08, 95 % confidence interval [CI] 1.07 - 4.06). Surveillance reduced CRC incidence in higher-risk participants (HR 0.35, 95 %CI 0.14 - 0.86) but not statistically significantly so in lower-risk participants (HR 0.41, 95 %CI 0.12 - 1.38).

CONCLUSION

 As previously demonstrated for hospital patients, screening participants classified as intermediate risk comprised two risk subgroups. Surveillance clearly benefited the higher-risk subgroup.

Long-term colorectal cancer incidence after adenoma removal and the effects of surveillance on incidence: a multicentre, retrospective, cohort study

OBJECTIVE

Postpolypectomy colonoscopy surveillance aims to prevent colorectal cancer (CRC). The 2002 UK surveillance guidelines define low-risk, intermediate-risk and high-risk groups, recommending different strategies for each. Evidence supporting the guidelines is limited. We examined CRC incidence and effects of surveillance on incidence among each risk group.

DESIGN

Retrospective study of 33 011 patients who underwent colonoscopy with adenoma removal at 17 UK hospitals, mostly (87%) from 2000 to 2010. Patients were followed up through 2016. Cox regression with time-varying covariates was used to estimate effects of surveillance on CRC incidence adjusted for patient, procedural and polyp characteristics. Standardised incidence ratios (SIRs) compared incidence with that in the general population.

RESULTS

After exclusions, 28 972 patients were available for analysis; 14 401 (50%) were classed as low-risk, 11 852 (41%) as intermediate-risk and 2719 (9%) as high-risk. Median follow-up was 9.3 years. In the low-risk, intermediate-risk and high-risk groups, CRC incidence per 100 000 person-years was 140 (95% CI 122 to 162), 221 (195 to 251) and 366 (295 to 453), respectively. CRC incidence was 40%-50% lower with a single surveillance visit than with none: hazard ratios (HRs) were 0.56 (95% CI 0.39 to 0.80), 0.59 (0.43 to 0.81) and 0.49 (0.29 to 0.82) in the low-risk, intermediate-risk and high-risk groups, respectively. Compared with the general population, CRC incidence without surveillance was similar among low-risk (SIR 0.86, 95% CI 0.73 to 1.02) and intermediate-risk (1.16, 0.97 to 1.37) patients, but higher among high-risk patients (1.91, 1.39 to 2.56).

CONCLUSION

Postpolypectomy surveillance reduces CRC risk. However, even without surveillance, CRC risk in some low-risk and intermediate-risk patients is no higher than in the general population. These patients could be managed by screening rather than surveillance.

Faecal immunochemical tests (FIT) versus colonoscopy for surveillance after screening and polypectomy: a diagnostic accuracy and cost-effectiveness study

OBJECTIVE

The English Bowel Cancer Screening Programme (BCSP) recommends 3 yearly colonoscopy surveillance for patients at intermediate risk of colorectal cancer (CRC) postpolypectomy (those with three to four small adenomas or one ≥10 mm). We investigated whether faecal immunochemical tests (FITs) could reduce surveillance burden on patients and endoscopy services.

DESIGN

Intermediate-risk patients (60-72 years) recommended 3 yearly surveillance were recruited within the BCSP (January 2012-December 2013). FITs were offered at 1, 2 and 3 years postpolypectomy. Invitees consenting and returning a year 1 FIT were included. Participants testing positive (haemoglobin ≥40 µg/g) at years one or two were offered colonoscopy early; all others were offered colonoscopy at 3 years. Diagnostic accuracy for CRC and advanced adenomas (AAs) was estimated considering multiple tests and thresholds. We calculated incremental costs per additional AA and CRC detected by colonoscopy versus FIT surveillance.

RESULTS

74% (5938/8009) of invitees were included in our study having participated at year 1. Of these, 97% returned FITs at years 2 and 3. Three-year cumulative positivity was 13% at the 40 µg/g haemoglobin threshold and 29% at 10 µg/g. 29 participants were diagnosed with CRC and 446 with AAs. Three-year programme sensitivities for CRC and AAs were, respectively, 59% and 33% at 40 µg/g, and 72% and 57% at 10 µg/g. Incremental costs per additional AA and CRC detected by colonoscopy versus FIT (40 µg/g) surveillance were £7354 and £180 778, respectively.

CONCLUSIONS

Replacing 3 yearly colonoscopy surveillance in intermediate-risk patients with annual FIT could reduce colonoscopies by 71%, significantly cut costs but could miss 30%-40% of CRCs and 40%-70% of AAs.

TRIAL REGISTRATION NUMBER

ISRCTN18040196; Results.