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Lumbar spinal stenosis, assessing failure and worsening after surgery. Identifying predictive factors with critical use of data from a national spine registry (NORspine)
Full text linkNorsk sammendrag
Spinal stenose er en vanlig lidelse som skyldes trang ryggmargskanal og karakteriseres av smerter i rygg og bein og redusert gangfunksjon. Operasjon er ofte nødvendig og spinal stenose er den hyppigste årsaken til ryggkirurgi i Norge (3, 23). Resultatene etter kirurgi er noe sprikende: de fleste blir bedre, noen blir ikke bedre, og enkelte blir verre (5, 6, 7).
Det er utfordrende å måle resultat etter behandling for smertetilstander fordi det ikke finnes klare konkrete endepunkt. Pasient-rapporterte resultater er sentrale, man kan bruke smerteskalar eller spørreskjema på funksjon og livskvalitet. Fortolkning av svar i skala-form kan være krevende, det fordres en viss endring på skalaene for at endringen skal være klinisk relevant. Man kan lette fortolkningen med å lage kategorier der pasientene klassifiseres som enten bedre, uendret eller verre.
Vi har brukt data fra Norsk kvalitetsregister for ryggkirurgi og analysert pasienter operert for spinal stenose. Registeret inneholder data om pasientforhold og plager før operasjon, operasjonstekniske forhold og resultater 3-og 12 måneder etter operasjon. Gjennom dette har vi tilegnet oss ny kunnskap om spinal stenose pasienter.
Registerdata er beheftet med flere usikkerhetsområder, mange pasienter faller fra og svarer ikke på oppfølgingene, og data kan i tillegg bli feilregistrert. Vi har derfor undersøkt kvaliteten på registerdata som ble brukt i denne doktorgradsavhandlingen.
Det er kjent at ikke alle pasienter blir kvitt plagene etter kirurgi for spinal stenose, og vi fant at om lag 20% rapporterte at plagene var uendret eller verre etter kirurgi. Videre fant vi de grenseverdiene som definerte mislykket kirurgi (uendret eller verre) og forverring på de mest brukte skalaene med størst nøyaktighet.
Vi testet samsvar av registerdata ved å kontrollere opp mot journaldata og fant at datakvaliteten i registeret var vekslende. Pasientrapporterte data og operasjonstekniske faktorer hadde høyt samsvar, mens andre helseforhold og komplikasjoner hadde dårligere samsvar med pasientjournalen. Pasienter som ikke svarte på oppfølgingsskjemaer fra registeret skilte seg noe fra de som svarte; de var litt yngre og oftere røykere. Resultatene etter operasjon var like i de to gruppene.
Den vanligste komplikasjonen til kirurgi for spinal stenose er rift på nervehinnen, dette medfører lekkasje av spinalvæske, eksponering av nervetråder og noen ganger behov for reoperasjon og forlenger sengeleie. Vi fant noe dårligere resultater etter operasjon hos pasienter som fikk rift på nervehinnen.
Det kan være vanskelig å beslutte om kirurgi er riktig for den enkelte pasient. Vi identifiserte noen faktorer som øker risikoen for mislykket kirurgi og forverring (alder over 70 år, tidligere ryggkirurgi og ryggsmerter over 12 mnd., samt noen sosioøkonomiske variabler). Disse faktorene kan bidra til bedre pasient informasjon og slik gi støtte til beslutning om operasjon eller ikke operasjon.
Vi håper våre resultater er nyttige for klinikere og at de bidrar til bedre informasjon til pasienter samt gode behandlingsvalg. Vi håper også resultatene kan gi grunnlag for videre forskning på ryggkirurgi.English abstract
Background
Results after surgery for lumbar spinal stenosis (LSS) vary; most patients improve, but some do not, and some even worsen. Some patients also suffer from complications. Previous studies have identified certain factors that may predict outcomes after surgery for LSS. Development in surgical technique may have reached a ceiling because new techniques fail to prove better; this emphasizes focus on careful patient selection to improve the overall results.
National medical registries collect a large number of data and reflect daily practice. Because of the large number of participants, registry studies are optimal for studying complications of surgery. However, registry data are vulnerable to wrong recordings and loss of follow-up. Hence, registry data should be assessed for bias before conclusions are drawn.
Methods
We reviewed patients operated on for LSS in Norway for ten years (2007-2017). Prospectively collected data from the NORspine registry was the foundation of the observational studies included in the thesis. We also supplemented registry data with data from patient records and performed a cross-sectional study.
We included patients treated over two years from four hospitals to assess data accuracy. Data was re-captured from electronic patient records, and we assessed the agreement between the two data sources using kappa statistics.
To assess potential bias due to loss to follow-up, we compared baseline variables between patients completing follow-up and those who did not. We also contacted patients lost to follow-up to see if they reported different clinical outcomes. We used simple descriptive statistics and compared baseline data and clinical outcomes between the groups with student T-tests.
We defined criteria for failure and worsening using a transition scale (Global Perceived Effect (GPE)) as an external anchor and receiver operating characteristic (ROC) curve analyses to identify the best cut-offs on PROMs commonly used to assess the effect of spine surgery. We also studied if a dural tear affected the clinical outcome, defined as failure or worsening, using logistic regression analyses and adjusting for possible confounding factors.
Finally, we tried to identify variables that could predict failure and worsening using multiple logistic regression analyses with the cut-offs identified earlier in our project. We selected baseline variables with acceptable accuracy according to an early part of our project.
Results
The study population comprised 11873 patients, and 8919 (75%) completed 12 months of follow-up. We reviewed 474 patient records to assess NORspine accuracy and the impact of loss to follow-up.
Patient-recorded variables and surgeon-reported surgical details displayed moderate to good accuracy; however, surgeon-reported complications and comorbidity were underreported. Patients lost to follow-up were younger and, more often, were smokers. However, there were no statistically significant differences in clinical outcomes. The following PROM cut-offs most accurately defined patient-reported failure (and
worsening): ODI final score of more than 31 (39), ODI percentage improvement of less than 20% (9%) and ODI improvement of less than 8 (4) points. These cut-offs had good to excellent accuracies (AUC= 0.86-0.91).
Dural tears occurred in nearly 5%. Patients who suffered a dural tear increased the odds of failure (and worsening) with an odds ratio of 1,45 (1,50).
After LSS surgery, a proportion of 33 % was defined as failure and 22 % as worse. Age over 70 years, previous spinal surgery, and duration of back pain over 12 months were essential baseline variables associated with failure and worsening (Odds ratio 1,85 – 2,21); socioeconomic factors also affected the odds for failure and worsening (OR 1,26 – 1,67).
Conclusions
There are concerns regarding data quality in the spine registry; data should be used and interpreted with care. Patients lost to follow-up reported similar clinical outcomes as those who completed follow-up, and missing data from loss to follow-up can most likely be treated as missing at random. Cut-offs for failure and worsening are accurate and can be used in future research and clinical work. LSS patients over 70 years, with previous spine surgery and duration of back pain over 12 months, had increased odds for failure and worsening; this could aid in patient selection
Development of a prognostic model for unfavorable outcome after lumbar microdiscectomy
Full text linkThe aim of this thesis was to develop a prognostic model for unfavorable outcome 12 months after surgical treatment of a lumbar disc herniation (lumbar microdiscectomy). While the surgical procedure is rather uniform, with little technical variation, the reported outcomes are quite heterogenous. This might be due to different expectations by patients, or due to suboptimal surgical indication as concluded by the treating surgeon. We aimed to translate evidence from a large national database to clinical practice (benchmark to bedside) by creating a prognostic model for the most commonly performed spinal surgery. The thesis is based on three papers. In papers I and II we created cutoffs for negative outcome after lumbar microdiscectomy, by Receiver Operating Curve (ROC) analyses of several Patient Reported Outcome Measures (PROMs) against the Global Perceived Effectiveness (GPE) scale. The Oswestry Disability Index (ODI), a PROM specific to spinal disorders, was able to identify two outcomes, namely Failure (patient feeling unchanged or worse) and Worsening (patient feeling much worse or worse than ever) 12 months after surgery. We found that the absolute ODI score after 12 months had the highest accuracy identifying these outcomes, and that the cutoff value was highly dependent on the preoperative ODI score. In paper III we created a prognostic matrix by means of logistic binary regression analyses with previously identified risk factors for negative outcome after lumbar microdiscectomy. The matrix contains six pathways, based on baseline ODI and which outcome is to be predicted (failure or worsening). The matrix showed acceptable discrimination and calibration values. Only model pathway predicting worsening in the population with a baseline ODI above the 75th percentile was not optimally calibrated, yielding an underestimation of the negative outcome rates. In summary, we have determined outcome criteria for unfavorable results 1 year after lumbar microdiscectomy, based on PROMs in a large national spine registry. We created a prognostic model predicting both failure and worsening 1 year after lumbar microdiscectomy based on the presence or absence of patient specific risk factors. The model could be used for evidence based shared decision making in clinical practice, and help set expectations for both the patient and the surgeon in regards to outcome
Is smoking associated with patient reported surgical-site infection after fusion surgery in the lumbar spine?
Full text linkIntroduction: Surgical site infection (SSI) is one of the most common complications in patients undergoing spine surgery. Associations between smoking and SSI have been found in previous studies, but with ambiguous results. This study was designed to compare the postoperative rate of SSI among smokers and non-smokers after fusion surgery in the lumbar spine and evaluate risk factors for SSI.
Methods and materials: This observational study includes 2546 patients from the Norwegian Registry for Spine Surgery (NORspine), operated with arthrodesis (fusion) surgery for degenerative disorders of the lumbar spine. Data were collected prospectively from the date of operation (baseline) and at 3 months of follow-up. The primary outcome was surgical site infection, reported by the patient responding to a standardized questionnaire.
Results: A total of 5.9% of the patients reported a SSI within three months after surgery. No association between smoking and SSI was found. ASA grade>2 (OR 2.07, 95%CI= 1.19-3.60, p= 0.01), lower age (OR 0.98, 95%CI=0.96-0.99 p9 days), only ASA grade >2 were significant for both groups. For the ones that stayed less than 10 days at the hospital also lower age (OR= 0.98, 95%CI=0.96-0.94, p=<0.01) and previously operated in the back (1.74, 95%CI= 1.13-2.69, p=0.01) were independent risk factors. The risk of developing a SSI increased 1.7 fold with a hospital stay of 10 days or more.
Conclusions: The rate of postoperative SSI in this study is in line with previous literature. No increased risk of SSI between smokers and non-smokers were found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Er det forskjell i behandlingsresultat mellom pasienter som besvarer spørreskjema om utfall etter nakkekirurgi og pasienter som ikke gjør det?
Full text linkBakgrunn og formål:
Oppgaven er en valideringsstudie basert på data fra Nasjonalt kvalitetsregister for rygg- og nakkekirurgi (NKR). Validiteten til kvalitetsregistre er avhengig av tilstrekkelig høy responsrate for at konklusjonene som trekkes angående effekt av en behandling skal være korrekte. Formålet med studien er å analysere om det er forskjell i behandlingsresultat mellom pasienter som besvarer oppfølgingsskjema per post ett år etter nakkekirurgi, og pasienter som ikke gjør det. Samtidig vil vi identifisere prediktorer for å ikke respondere.
Metode:
Totalt ble 334 pasienter som fortløpende ble operert for degenerative nakkelidelser ved ti norske sykehus inkludert i studien. 238 av disse responderte på standard oppfølging med spørreskjema per post. Vi forsøkte å komme i kontakt med de 96 pasientene som ikke reponderte for å gjennomføre et strukturert telefonintervju. Utfallsmålene var forbedring i armsmerte, nakkesmerte, helserelatert livskvalitet (EQ-5D-3L), samt pasientrapportert nytte av operasjonen.
Resultat:
Vi fant ingen signifikante forskjeller i utfall mellom respondentene (71,3 % av pasientene) og telefonrespondentene (18,9 % av pasientene). 33 pasienter var utilgjengelig for oppfølging (9,9 % av pasientene). En større andel av telefonrespondentene rapporterte om komplikasjoner etter tolv måneder, men tre måneders data viste ingen forskjell i andel komplikasjoner mellom gruppene. Multivariat analyse viste at lavere alder (OR 0,96, 95 % KI 0,93 – 0,98 per år), annet morsmål enn norsk (OR 2,96, 95 % KI 1,37 – 6,41) og tidligere nakkoperasjon (OR 1,91, 95 % KI 1,05-3,50) var assosiert med økt sannsynlighet for å ikke respondere på den ordinære oppfølgingen.
Konklusjon:
Vi fant ingen forskjell i behandlingsresultat mellom respondenter og telefonrespondenter 12 måneder etter nakkekirurgi. En andel på 29% som ikke responderer på oppfølging etter nakkekirurgi fører ikke til at det trekkes feil konklusjoner angående behandlingseffekt
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Lumbosacral radiculopathy managed in multidisciplinary back clinics. Diagnostic accuracy, prognostic factors and efficacy of epidural injection therapy.
Full text linkThe accuracy of individual clinical index tests used to predict imaging findings of nerve root impingement in patients with chronic lumbar radiculopathy is low when applied in specialized care, but clinicians’ overall evaluation improves diagnostic accuracy slightly. The diagnostic accuracy of individual index tests was low with no tests reaching positive LR >4.0 or negative LR <0.4. The overall clinical evaluation was slightly more accurate, with a positive LR of 6.28 (95% CI 1.06–37.21) for L4, 1.74 (95% CI 1.04–2.93) for L5, and 1.29 (95% CI 0.97–1.72) for S1 nerve root impingement. The tests are not very helpful in clarifying the cause of radicular pain, and are therefore inaccurate for guidance in the diagnostic workup of the patients.
Lower age, higher education, working full-time and low fear avoidance beliefs each predict a better outcome of chronic unilateral lumbar radiculopathy. Specifically, lower age and low fear avoidance predict a better functional outcome and less back pain, while higher education and working full-time predict less leg pain.
Treating chronic lumbar radiculopathy with either caudal epidural steroid injections or epidural saline cannot be recommended. Compared to a sham procedure, we found no evidence of any clinically important treatment effect of caudal epidural steroid or saline injections in patients with chronic lumbar radiculopathy. The differences in outcome for the epidural saline intervention group compared to the sham intervention group were −0.5 (−6.3, 5.4) at the 6-week follow-up, 1.4 (−4.5, 7.2) at the 12-week follow-up, and −1.9 (−8.0, 4.3) at the 52-week follow-up. The differences in outcome for the epidural steroid intervention group compared to the sham intervention group were −2.9 (−8.7, 3.0) at the 6-week follow-up, 4.0 (−1.9, 9.9) at the 12-week follow-up, and 1.9 (−4.2, 8.0) at the 52-week follow-up
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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