ELIZA cgi-bash version rev. 1.90
- Medical English LInking keywords finder for the PubMed Zipped Archive (ELIZA) -

return kwic search for studies out of >500 occurrences
532339 occurrences (No.23 in the rank) during 5 years in the PubMed. [no cache] 500 found
298) Nevertheless, causal inference models should become standard along side the currently applied standard methods, especially in studies with high non-compliance due to changes in therapy and substantial loss to follow-up.
--- ABSTRACT ---
PMID:24203687 DOI:10.1055/s-0033-1355405
2015 Gesundheitswesen (Bundesverband der Arzte des Offentlichen Gesundheitsdienstes (Germany))
* [Time-dependent confounding in the estimation of treatment effects in randomised trials with multimodal therapies--an illustration of the problem of time-dependent confounding by causal graphs].
- Biased effect estimates induced by unconsidered confounding variables are a known problem in observational studies. Selection bias, resulting from non-random sampling of study participants, is widely recognised as a problem in case-control and cross-sectional studies. In contrast, possible bias in randomised controlled trials (RCTs) is mostly ignored. This paper illustrates, by applying directed acyclic graphs (DAGs), possible bias in the effect estimates of first-line therapy, caused by subsequent changes in therapy (time-dependent confounding). Possible selection bias, induced by not only random loss to follow-up, will be explained as well using DAGs. Underlying assumptions of standard methods usually used to analyse RCTs (like intention-to-treat, per-protocol) are shown and it is explained why effect estimates may be biased in RCTs, if only these conventional methods are used. Adequate statistical methods (causal inference models as marginal structural models and structural nested models) exist. Higher documentary efforts, however, are necessary, because any changes in medication, loss to follow-up as well as reasons for such changes need to be documented in detail as required by these advanced statistical methods. Nevertheless, causal inference models should become standard along side the currently applied standard methods, especially in studies with high non-compliance due to changes in therapy and substantial loss to follow-up. Possible bias cannot be excluded if similar results are obtained from both methods. However, study results should be interpreted with caution if they differ between both approaches.
--- ABSTRACT END ---
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(1)61 have (14)8 with (27)3 demonstrate (40)2 including
(2)47 *null* (15)7 should (28)3 for (41)2 indicated
(3)32 of (16)6 is (29)3 however, (42)2 investigating
(4)26 are (17)6 we (30)3 performed (43)2 involving
(5)26 on (18)5 suggest (31)3 reported (44)2 it
(6)19 in (19)5 the (32)3 since (45)2 or
(7)17 were (20)4 as (33)3 which (46)2 provide
(8)16 and (21)4 demonstrated (34)2 about (47)2 published
(9)15 to (22)4 evaluating (35)2 also (48)2 regarding
(10)10 showed (23)4 from (36)2 can (49)2 targeting
(11)8 revealed (24)4 indicate (37)2 concerning (50)2 tested
(12)8 that (25)4 show (38)2 demonstrating (51)2 used
(13)8 using (26)3 based (39)2 has (52)2 was

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--- WordNet output for studies --- Overview of noun study The noun study has 10 senses (first 8 from tagged texts) 1. (90) survey, study -- (a detailed critical inspection) 2. (17) study, work -- (applying the mind to learning and understanding a subject (especially by reading); "mastering a second language requires a lot of work"; "no schools offer graduate study in interior design") 3. (6) report, study, written report -- (a written document describing the findings of some individual or group; "this accords with the recent study by Hill and Dale") 4. (6) study -- (a state of deep mental absorption; "she is in a deep study") 5. (6) study -- (a room used for reading and writing and studying; "he knocked lightly on the closed door of the study") 6. (3) discipline, subject, subject area, subject field, field, field of study, study, bailiwick -- (a branch of knowledge; "in what discipline is his doctorate?"; "teachers should be well trained in their subject"; "anthropology is the study of human beings") 7. (2) sketch, study -- (preliminary drawing for later elaboration; "he made several studies before starting to paint") 8. (1) cogitation, study -- (attentive consideration and meditation; "after much cogitation he rejected the offer") 9. study -- (someone who memorizes quickly and easily (as the lines for a part in a play); "he is a quick study") 10. study -- (a composition intended to develop one aspect of the performer's technique; "a study in spiccato bowing") Overview of verb study The verb study has 6 senses (first 6 from tagged texts) 1. (73) analyze, analyse, study, examine, canvass, canvas -- (consider in detail and subject to an analysis in order to discover essential features or meaning; "analyze a sonnet by Shakespeare"; "analyze the evidence in a criminal trial"; "analyze your real motives") 2. (17) study -- (be a student; follow a course of study; be enrolled at an institute of learning) 3. (15) study, consider -- (give careful consideration to; "consider the possibility of moving") 4. (13) learn, study, read, take -- (be a student of a certain subject; "She is reading for the bar exam") 5. (5) study, hit the books -- (learn by reading books; "He is studying geology in his room"; "I have an exam next week; I must hit the books now") 6. (2) study, meditate, contemplate -- (think intently and at length, as for spiritual purposes; "He is meditating in his study") --- WordNet end ---