Nurse study: Are the results of the study valid?
Primary guide:
Were there clearly identified comparison groups that were similar with respect to important determinants of outcome, other than the one of interest?
-Yes there were clearly definied comparison groups what were overall similar. Differences between the groups were identified and addressed within the paper.
Were the outcomes and exposures measured in the same way in the groups being compared?
-Yes
Was follow up sufficiently long and complete?
– follow up was long at 16 years and complete in that the vast majority were not lost to follow up. However, I’m not sure if 16 years is truly sufficient as some individuals take these medications for seemingly indefinite periods of time. You would hope this is long enough but is hard for me to truly “know”.
Secondary guide:
Is the temporal relationship correct?
-yes.
Is there a dose-response gradient?
-yes, for estrogen therapy there was an dose response gradient on CV outcomes within the study.
| Title and abstract | 1 | (a) Indicate the study’s design with a commonly used term in the title or the abstract -Yes-in the abstract |
| (b) Provide in the abstract an informative and balanced summary of what was done and what was found -Yes | ||
| Introduction | ||
| Background/rationale | 2 | Explain the scientific background and rationale for the investigation being reported -Epidemiologic data suggest estrogen alone in PMW decreases CAD. Little data on combined HRT. Experimental data suggesting progestin component diminished cardioprotective effects of estrogen only HRT. |
| Objectives | 3 | State specific objectives, including any prespecified hypotheses -Relation between combined HRT and CVD. No explicit hypothesis in intro |
| Methods | ||
| Study design | 4 | Present key elements of study design early in the paper -Mailed questionnaire to ~122k women nurses aged 30-55. Followed up with questionnaires and confirmed- responses of interest with medical records if possible. |
| Setting | 5 | Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection 1976-1992, nurses who responded to a mail in questionnaire. Exposure of HRT, diet, physical activity etc. |
| Participants | 6 | Give the eligibility criteria, and the sources and methods of selection of participants. Describe methods of follow-up -Female nurses who responded. Follow with biennial questionaires. |
| Variables | 7 | Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable “Cardiovascular disease was defined as nonfatal myocardial infarction, fatal coronary disease, coronary-bypass surgery or angioplasty, and fatal or nonfatal stroke occurring during the period between the return of the 1976 questionnaire and June 1, 1992.” The rest was explained under “documentation of CVD” Excluding all MI of indeterminate age seemed like an interesting population to exclude. Patient’s with “silent Mis” can still suffer significant morbidity and would have been interested to study their correlation with HRT. If the person had mentioned a history of MI on their initial survey, they would have been excluded but these individuals were included and then later excluded. |
| Data sources/ measurement | 8* | For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group – Criteria used to verify CVD was per WHO guidelines. Confirming death via CVD were confirmed with more than just a death certificate designation. |
| Bias | 9 | Describe any efforts to address potential sources of bias -they adjusted for variables such as age, age at menopause, body-mass index (the weight in kilograms divided by the square of the height in meters), cigarette smoking, hypertension, diabetes, elevated cholesterol levels, and many for |
| Study size | 10 | Explain how the study size was arrived at -By the number of female nurses within the age range who responded to a mail in questionnaire |
| Quantitative variables | 11 | Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why -saturated-fat intake (in quintiles), alcohol use (none, 5 g, 5 to 14.9 g, or 15 g per day), use of vitamin E (none, 100 IU, 100 to 299 IU, 300 to 599 IU, or 600 IU per day) or multivitamins (yes or no), use of aspirin (none or 1 to 6 pills or 7 pills a week), and physical activity (none or at least once per week) – these quantitative variables were grouped but there was no expansion into the rationale of each grouping criteria. |
| Statistical methods | 12 | Describe all statistical methods, including those used to control for confounding -Each pariticpant was allocated to categories of hormone use by person-months according to 1976 data and updated every 2 years -Proportional-hazards models were used to calculate relative risks for things such as age and BMI |
| Describe any methods used to examine subgroups and interactions -relative risk was used as the measure of association. The used five year categories for age specific rates to calculate age-adjusted relative risk with 95% CI.” Tests of trends across categories of exposure were calculated by treating the levels of exposure as a continuous, ordinal variable in the regression model.” | ||
| (c) Explain how missing data were addressed | ||
| If applicable, explain how loss to follow-up was addressed I saw little to no mention | ||
| (e) Describe any sensitivity analyses RR w/ 95%CI | ||
| Results | ||
| Participants | 13* | Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed -21.726 included in 1976 and 37-611 added during follow up for a total of 662,891 person years of follow up between 1976-1992 |
| Give reasons for non-participation at each stage -initiall excluded if they reported h/o stroke, MI, angina or cancer and subsequently excluded if they reported any of these on a later questionnaire | ||
| ( | ||
| Descriptive data | 14* | (a) Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential confounders as above |
| Indicate number of participants with missing data for each variable of interest -3.2% had missing data related to hormone use | ||
| (c) Summarise follow-up time (eg, average and total amount) | ||
| Outcome data | 15* | Report numbers of outcome events or summary measures over time -584 nonfatal myocardial infarctions, 186 deaths due to coronary disease, 572 strokes (285 ischemic events, 155 subarachnoid hemorrhages, and 132 other or unspecified types), and 553 instances of coronary surgery or angioplasty |
| Main results | 16 | (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were included -yes |
| Report category boundaries when continuous variables were categorized -n/a | ||
| If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period -n/a | ||
| Other analyses | 17 | Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses -n/a |
| Discussion | ||
| Key results | 18 | Summarise key results with reference to study objectives -These were summarized |
| Limitations | 19 | Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias -yes |
| Interpretation | 20 | Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence -yes |
| Generalisability | 21 | Discuss the generalisability (external validity) of the study results -Yes, and is very generalizable based on the included population’s co. morbidities and prevalent use of OCPs |
| Other information | ||
| Funding | 22 | Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on which the present article is based – Funding not discussed. Other studies upon what this is based were. |
Statin and Cataracts:
Are the results of the study valid?
Primary guide:
Were there clearly identified comparison groups that were similar with respect to important determinants of outcome, other than the one of interest
-yes
Were the outcomes and exposures measured in the same way in the groups being compared?
-yes
Was follow up sufficiently long and complete?
Secondary guide:
Is the temporal relationship correct?
-yes
Is there a dose-response gradient?
-No. Dosage were not included. Also not included was the potency of the statins.
| Item No | Recommendation | ||||
| Title and abstract | 1 | Indicate the study’s design with a commonly used term in the title or the abstract -Yes | |||
| Provide in the abstract an informative and balanced summary of what was done and what was found -Yes | |||||
| Introduction | |||||
| Background/rationale | 2 | Explain the scientific background and rationale for the investigation being reported -Yes | |||
| Objectives | 3 | State specific objectives, including any prespecified hypotheses -Yes, states objectives but no hypothesis. | |||
| Methods | |||||
| Study design | 4 | Present key elements of study design early in the paper -Yes | |||
| Setting | 5 | Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection -Yes | |||
| Participants | 6 | Give the eligibility criteria, and the sources and methods of case ascertainment and control selection. Give the rationale for the choice of cases and controls -Yes | |||
| Variables | 7 | Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable -Very poor description of the variables within the analysis. | |||
| Data sources/ measurement | 8* | For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group – not really given | |||
| Bias | 9 | Describe any efforts to address potential sources of bias -bias was addressed by mentioning the statistical adjustment for age, gender, DM, etc. | |||
| Study size | 10 | Explain how the study size was arrived at -yes, clear | |||
| Quantitative variables | 11 | Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why -handled by way of multivariate analysis. | |||
| Statistical methods | 12 | Describe all statistical methods, including those used to control for confounding -yes | |||
| Describe any methods used to examine subgroups and interactions -yes | |||||
| Explain how missing data were addressed -yes | |||||
| ( | |||||
| Describe any sensitivity analyses “-sensitivity analysis to study what effect excluding residents who had used statins for less than a year would have on our results” | |||||
| Results | |||||
| Participants | 13* | Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed -yes | |||
| Give reasons for non-participation at each stage yes | |||||
| Descriptive data | 14* | Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential confounders -see table 1 | |||
| Indicate number of participants with missing data for each variable of interest -not present | |||||
| Outcome data | * | Report numbers in each exposure category, or summary measures of exposure -yes | |||
| Main results | 16 | Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were included -yes | |||
| Discussion | |||||
| Key results | 18 | Summarise key results with reference to study objectives -yes | |||
| Limitations | 19 | Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias -yes | |||
| Interpretation | 20 | Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence -present and caution interpretation of their results | |||
| Generalisability | 21 | Discuss the generalisability (external validity) of the study results -addressed generalizability | |||
| Other information | |||||
| Funding | 22 | Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on which the present article is based -yes | |||
Report your critical appraisal findings in your blog post. Is the study methodologically sound? Does it have any flaws? What effect, if any, does any flaw have on the results? Your post for this portion of the assignment should have 2 sections (one for each study): one for the results from your critical appraisal and one discussing if you think the study is methodologically valid and why/why not. Each critical appraisal section should have the questions from the tool and your answer. Elaborate why you answered each question as you did.
- Compare and contrast the User’s Guides and STROBE checklists. Which do you think is best and why? Which is most user friendly and why? Which do you plan to use in the future when you read observational studies?
Critical appraisal: I believe both studies were methodologically sound. I did not note any tremendous, disqualifying flaws though what flaws I did find are noted above. Each of these studies seemed to be designed appropriately.
I felt as though User’s guide was a superior tool to use in analyzing these studies. STROBE was cumbersome to use and I found myself focusing on checking the boxes more than actually analyzing the studies. I used the user’s guide second in the HRT paper and first in the Statin paper and felt as though I had a more thorough big picture understanding of the statin paper after my first pass. I see myself using the user’s guide for observational studies as this is simply more *user* friendly.
Evidence Blaked Medicine 