Evaluating the Safety of Tenecteplase Versus Alteplase for Acute Ischemic Stroke

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article requires revision in the sections describing the sample and results. Please answer the following questions.

Provide evidence that the patient samples were balanced in composition.
It is claimed that tenecteplase may be safe for patients with moderate symptoms, but the study  included patients with varying degrees of severity. Does the lack of stratification by stroke severity affect interpretation of the results?
Were other comorbidities (eg, hypertension and diabetes) that might influence the risk of bleeding taken into account?
Why was the mRS at discharge better in the tenecteplase group, even though other outcomes (hemorrhage and mortality) did not differ? Could unaccounted-for factors (e.g., different rehabilitation) have played a role?

Author Response

1. Provide evidence that the patient samples were balanced in composition.
   1. Response: The patient sample baseline characteristics are shown in Table 1, and further description has been added in the sentences highlighted above Table 1. Similar characteristics included a median [IQR] age of 65 [53-75] and 64 [52-75] years, median [IQR] NIHSS of 7 [3-14] and 8 [4-13], and median [IQR] hemoglobin of 13.4 [12.1-14.5] and 13.3 [12.4-14.5] g/dL, respectively. The median stroke onset to thrombolytic administration time was 2 hours in both groups.
2. It is claimed that tenecteplase may be safe for patients with moderate symptoms, but the study included patients with varying degrees of severity. Does the lack of stratification by stroke severity affect interpretation of the results
   1. Response. Thank you for pointing this out. The sentence in the Abstract was revised to include “mild to moderate” instead of just “moderate” severity to align with the “mild to moderate” severities mentioned in the Discussion and Conclusion. In addition, we acknowledged the need for stratification by stroke severity in our Limitations section.
3. Were other comorbidities (eg, hypertension and diabetes) that might influence the risk of bleeding taken into account?
   1. Response: No, elaboration was added in the Discussion regarding risk factors for bleeding.
4. Why was the mRS at discharge better in the tenecteplase group, even though other outcomes (hemorrhage and mortality) did not differ? Could unaccounted-for factors (e.g., different rehabilitation) have played a role?
   1. Response: Thank you for pointing this out. Unfortunately, we only had 38 patients with a documented mRS at discharge. While the results were statistically significant, as another reviewer pointed out, the mRS in this case are not deemed clinically significant and should be considered exploratory and subject to a high risk of bias.

Reviewer 2 Report

Comments and Suggestions for Authors Manuscript ID: ecm-3733490

Dear Authors,

                     It's very crucial to study about the safety profile of individual drugs. It is even more important to conduct comparative study of drugs used in the domain of emergency / critical care medicine. I have a few concerns to share here.

Comments:

1. Rewrite these lines a bit clearly for the readers

2. Formatting error: over 5 seconds.7

3. Correct this: "emergent settings"

4. These lines of text seem incomplete. Modify them by adding more detail. "Current  evidence comparing tenecteplase and alteplase suggests greater efficacy with  tenecteplase and similar safety profiles."

5. Add more information here : "was made at the study institutions in March 2023."

6. Write this paragraph clearly: "This was a multicenter, retrospective cohort study 

that involved 11 community and academic hospitals within the Memorial Hermann 

Health System in the greater Houston area. Based on the Texas Department of State 

Health Services, 4 hospitals are comprehensive stroke centers, 4 are primary-

level III stroke centers, and 3 are primary level II stroke centers."

7. Add full form of IQR

8. In what basis those patients were selected for Tenecteplase Group

 

 

Comments on the Quality of English Language

Needs little refinement.

Author Response

1. Rewrite these lines a bit clearly for the readers
   1. Formatting error: over 5 seconds.7
      1. Response: Thank you for pointing this out. This has been corrected.
   2. Correct this: "emergent settings"
      1. Response: Thank you for pointing this out. This has been corrected.
2. These lines of text seem incomplete. Modify them by adding more detail. "Current evidence comparing tenecteplase and alteplase suggests greater efficacy with tenecteplase and similar safety profiles.”
   1. Response: Thank you for this suggestion. We have expanded on these lines of text by referencing a review article by Alhadid and colleagues. Please refer to highlighted lines 58-62 in the revised manuscript.
3. Add more information here : "was made at the study institutions in March 2023."
   1. Response: We have specified the “Memorial Herman Health System”.
4. Write this paragraph clearly: "This was a multicenter, retrospective cohort study that involved 11 community and academic hospitals within the Memorial Hermann Health System in the greater Houston area. Based on the Texas Department of State Health Services, 4 hospitals are comprehensive stroke centers, 4 are primary-level III stroke centers, and 3 are primary level II stroke centers."
   1. Response: Thank you for this suggestion. We have revised this paragraph. Please refer to highlighted lines 70-75 in the revised manuscript.
5. Add full form of IQR
   1. Response: We have added it at first mention of IQR in Results (i.e. line 113).
6. In what basis those patients were selected for Tenecteplase Group
   1. Response: We have expanded on this matter in the Materials and Methods section. Patients who received alteplase were selected from the 3-month time period prior to the transition to tenecteplase as the primary thrombolytic for acute ischemic stroke in the health system, and patients who received tenecteplase were selected from the 3-month time period immediately following the change.

Reviewer 3 Report

Comments and Suggestions for Authors

1. The comparison of tenecteplase and alteplase, including key safety outcomes like 24-hour hemorrhagic conversion, has been the subject of many large, prospective, multicenter randomized controlled trials. This existing body of high-level evidence substantially diminishes the novelty of the present study's primary objective. The Introduction should be revised to more clearly articulate the specific gap in the literature that this study aims to fill. Is the contribution its focus on the "real-world" implementation challenges during a system-wide transition? Is it to assess outcomes in a population not well-represented in the RCTs? Without a clear statement of what is new, the rationale for the study is weakened.
2. The authors candidly state in the Statistical Analysis section (lines 91-92) that a power analysis required 1,176 patients to achieve 80% power, whereas this study included only 173. This is a critical limitation. As the study is severely underpowered, the failure to detect a statistically significant difference in the primary outcome (hemorrhagic conversion, p=0.79) cannot be reliably interpreted as evidence of equivalence or non-inferiority. It is highly likely to be a Type II error (false negative). Recommendation:The conclusion in the Abstract must be rephrased to reflect this uncertainty. For instance: "In this underpowered study, we did not observe a statistically significant difference in the rate of 24-hour hemorrhagic conversion between the tenecteplase and alteplase groups."
3. A significant baseline imbalance was noted in the use of antiplatelet therapy within 24 hours of thrombolysis (6.9% in the tenecteplase group vs. 0% in the alteplase group, p=0.03). This is a critical confounding factor, as early antiplatelet administration is a known risk for increased bleeding. Although the primary outcome showed no difference, this imbalance itself requires a more in-depth discussion. The authors' proposed explanation regarding default medication timing in order entry is plausible but requires further elaboration. The Discussion section must explore how this imbalance could have potentially biased the safety outcomes. Did it predispose the tenecteplase group to a higher bleeding risk, thereby masking a potential safety benefit, or was its effect negligible in this small sample? A more robust discussion is necessary.
4. The study reports a statistically significant improvement in mRS scores at discharge for the tenecteplase group (p<0.01) and lists it as a significant secondary outcome. However, the authors correctly acknowledge that these data were subject to substantial missingness (analysis based on only n=38 patients) and inconsistent documentation (lines 121-122). Reporting this finding with a p-value of <0.01 is highly problematic and misleading given the severe risk of selection bias. It is strongly recommended that this finding be removed from the list of significant outcomes in the Abstract. In the Resultsand Discussion, this observation should be framed as exploratory, subject to a high risk of bias.
5. The results show a trend towards higher mortality in the alteplase group (6.9%) compared to the tenecteplase group (1.1%), with a p-value of 0.06 (lines 119-120 and Table 2). While not reaching the conventional threshold for statistical significance, this is a noteworthy trend for a critical safety endpoint. The Discussion should address this trend. The authors should explore potential explanations, such as subtle baseline differences in stroke severity not captured by the median NIHSS, other unmeasured confounders, or the possibility of it being a chance finding. Omitting a discussion of this important safety signal weakens the manuscript's rigor.
6. The patient flow diagram (Figure 1) reveals a notable imbalance in exclusions for "Med not given" (n=10 in the tenecteplase arm vs. n=3 in the alteplase arm). This discrepancy may be meaningful. The authors should consider discussing whether this reflects a "learning curve" or other logistical challenges associated with the introduction of a new agent (e.g., pharmacist/physician unfamiliarity, preparation delays). A brief discussion on this point would enhance the practical relevance of the study for other institutions undergoing a similar transition.
7. On line 93, the text reads "a<0.05". The standard notation is "p < 0.05". Please check and correct this throughout the manuscript for consistency.

Author Response

1. The comparison of tenecteplase and alteplase, including key safety outcomes like 24-hour hemorrhagic conversion, has been the subject of many large, prospective, multicenter randomized controlled trials. This existing body of high-level evidence substantially diminishes the novelty of the present study's primary objective. The Introduction should be revised to more clearly articulate the specific gap in the literature that this study aims to fill. Is the contribution its focus on the "real-world" implementation challenges during a system-wide transition? Is it to assess outcomes in a population not well-represented in the RCTs? Without a clear statement of what is new, the rationale for the study is weakened.
   1. Response: We appreciate the reviewer’s knowledge of the literature in this subject area. We believe our study adds to the body of literature by discussing the clinical implications of a real world implementation of tenecteplase as the primary thrombolytic for acute ischemic stroke across a robust health system.
2. The authors candidly state in the Statistical Analysis section (lines 91-92) that a power analysis required 1,176 patients to achieve 80% power, whereas this study included only 173. This is a critical limitation. As the study is severely underpowered, the failure to detect a statistically significant difference in the primary outcome (hemorrhagic conversion, p=0.79) cannot be reliably interpreted as evidence of equivalence or non-inferiority. It is highly likely to be a Type II error (false negative).

Recommendation: The conclusion in the Abstract must be rephrased to reflect this uncertainty. For instance: "In this underpowered study, we did not observe a statistically significant difference in the rate of 24-hour hemorrhagic conversion between the tenecteplase and alteplase groups."

1. Response: Thank you for pointing this out and for even providing a recommendation on how to rephrase our conclusion. We added in our Limitations section explaining power was not met. The timing of the transition to tenecteplase limited the study to only 3 months of data post-implementation. Further details can be found in lines 210-214 of the revised manuscript. We did revise our conclusion to reflect the reviewer’s recommendation.

3. A significant baseline imbalance was noted in the use of antiplatelet therapy within 24 hours of thrombolysis (6.9% in the tenecteplase group vs. 0% in the alteplase group, p=0.03). This is a critical confounding factor, as early antiplatelet administration is a known risk for increased bleeding. Although the primary outcome showed no difference, this imbalance itself requires a more in-depth discussion. The authors' proposed explanation regarding default medication timing in order entry is plausible but requires further elaboration. The Discussion section must explore how this imbalance could have potentially biased the safety outcomes. Did it predispose the tenecteplase group to a higher bleeding risk, thereby masking a potential safety benefit, or was its effect negligible in this small sample? A more robust discussion is necessary.
   1. Response: Thank you for pointing out these findings. We have added to this discussion is lines 228-238 in the revised manuscript.
4. The study reports a statistically significant improvement in mRS scores at discharge for the tenecteplase group (p<0.01) and lists it as a significant secondary outcome. However, the authors correctly acknowledge that these data were subject to substantial missingness (analysis based on only n=38 patients) and inconsistent documentation (lines 121-122). Reporting this finding with a p-value of <0.01 is highly problematic and misleading given the severe risk of selection bias. It is strongly recommended that this finding be removed from the list of significant outcomes in the Abstract. In the Results and Discussion, this observation should be framed as exploratory, subject to a high risk of bias.
   1. Response: While we acknowledge the reviewer’s concern of reporting mRS scores at discharge as statistically significant, we believe it is still pertinent to report as it is one of the most well documented outcomes of patients’ functional status post-stroke across stroke literature. We did caution the readers to only consider it exploratory due to the limited sample size and offer suggestions on how to increase reporting.
5. The results show a trend towards higher mortality in the alteplase group (6.9%) compared to the tenecteplase group (1.1%), with a p-value of 0.06 (lines 119-120 and Table 2). While not reaching the conventional threshold for statistical significance, this is a noteworthy trend for a critical safety endpoint. The Discussion should address this trend. The authors should explore potential explanations, such as subtle baseline differences in stroke severity not captured by the median NIHSS, other unmeasured confounders, or the possibility of it being a chance finding. Omitting a discussion of this important safety signal weakens the manuscript's rigor.
   1. Response: We appreciate the reviewer’s comments, however, we concluded to not comment on any trends towards significance on any of our outcomes at the risk of making misleading conclusions and inflating significance.
6. The patient flow diagram (Figure 1) reveals a notable imbalance in exclusions for "Med not given" (n=10 in the tenecteplase arm vs. n=3 in the alteplase arm). This discrepancy may be meaningful. The authors should consider discussing whether this reflects a "learning curve" or other logistical challenges associated with the introduction of a new agent (e.g., pharmacist/physician unfamiliarity, preparation delays). A brief discussion on this point would enhance the practical relevance of the study for other institutions undergoing a similar transition.
   1. Response: Thank you for this suggestion. Please see highlighted lines 215-219 in the revised manuscript on an explanation on the discrepancies.
7. On line 93, the text reads "a<0.05". The standard notation is "p < 0.05". Please check and correct this throughout the manuscript for consistency.
   1. Response: Thank you for pointing this out. We changed to α = 0.05 to represent significance level.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

After considering the reviewer's comments and the authors' changes to the manuscript, I believe the article is ready for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

     I could see that you have modified things as per the suggestions.

    Spotted a few formatting errors in the revised manuscript, correct them

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed all of my previous concerns. I have no further comments.