You will be provided with a reference and some statements. Please determine whether each statement is 'supported', 'unsupported', or 'unknown' with respect to the reference. Please note:
First, assess whether the reference contains any valid content. If the reference contains no valid information, such as a 'page not found' message, then all statements should be considered 'unknown'.
If the reference is valid, for a given statement: if the facts or data it contains can be found entirely or partially within the reference, it is considered 'supported' (data accepts rounding); if all facts and data in the statement cannot be found in the reference, it is considered 'unsupported'.

You should return the result in a JSON list format, where each item in the list contains the statement's index and the judgment result, for example:
[
    {
        "idx": 1,
        "result": "supported"
    },
    {
        "idx": 2,
        "result": "unsupported"
    }
]

Below are the reference and statements:
<reference>
1. BMC Public Health. 2023 Nov 1;23(1):2138. doi: 10.1186/s12889-023-17018-3.

Association of serum copper (Cu) with cardiovascular mortality and all-cause 
mortality in a general population: a prospective cohort study.

Li X(#)(1), Ling J(#)(2), Hu Q(1), Fang C(1), Mei K(3), Wu Y(1), Huang J(1), 
Ling Q(1), Chen Y(2), Yu P(2), Liu X(4)(5)(6), Li J(7).

Author information:
(1)Department of Cardiovascular Medicine, The Second Affiliated Hospital of 
Nanchang University, Nanchang, 330006, China.
(2)Department of Endocrinology Medicine, The Second Affiliated Hospital of 
Nanchang University, Nanchang, China.
(3)Department of Anesthesiology, The People's Hospital of Shanggrao, Shanggrao, 
Jiangxi, China.
(4)Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen 
University, Guangzhou, Guangdong, China. liux587@mail.sysu.edu.cn.
(5)Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, 
Guangzhou, Guangdong, China. liux587@mail.sysu.edu.cn.
(6)Guangzhou Key Laboratory of Molecular Mechanism and Translation in Major 
Cardiovascular Disease, Guangdong Provincial Key Laboratory of Malignant Tumor 
Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA 
Medicine, Guangzhou, Guangdong, China. liux587@mail.sysu.edu.cn.
(7)Department of Cardiovascular Medicine, The Second Affiliated Hospital of 
Nanchang University, Nanchang, 330006, China. ljx912@126.com.
(#)Contributed equally

BACKGROUND: Copper (Cu) homeostasis and Cu-induced cell death are gaining 
recognition as crucial processes in the pathogenesis of cardiovascular disease 
(CVD). Circulating Cu associated with CVD and mortality is yet to be fully 
elucidated.
OBJECTIVE: This national prospective cohort study is to estimate relationship 
between serum Cu and the risk of CVD and all-cause mortality.
METHODS: This study included participants from the National Health and Nutrition 
Examination Survey 2011-2016. Weighted Cox proportional hazards regression 
analysis and exposure-response curves were applied.
RESULTS: This included 5,412 adults, representing 76,479,702 individuals. During 
a mean of 5.85 years of follow-up (31,653 person-years), 96 CVD and 356 
all-cause mortality events occurred. Age and sex-adjusted survival curves showed 
that individuals with higher levels of serum Cu experienced increased CVD and 
all-cause death rates (tertiles, p < 0.05). Compared with the participant in 
tertile 1 of serum Cu (< 16.31 mol/L), those in tertile 3 (≥ 19.84 mol/L) were 
significantly associated with CVD mortality (HR: 7.06, 95%CI: 1.85,26.96), and 
all-cause mortality (HR: 2.84, 95% CI: 1.66,4.87). The dose-response curve 
indicated a linear relationship between serum Cu and CVD mortality (p 
-nonlinear = 0.48) and all-cause (p -nonlinear = 0.62). A meta-analysis included 
additional three prospective cohorts with 13,189 patients confirmed the 
association between higher serum Cu and CVD (HR: 2.08, 95% CI: 1.63,2.65) and 
all-cause mortality (HR: 1.89, 95%CI: 1.58,2.25).
CONCLUSION: The present study suggests excessive serum Cu concentrations are 
associated with the risk of CVD and all-cause mortality in American adults. Our 
findings and the causal relationships require further investigation.

© 2023. The Author(s).

DOI: 10.1186/s12889-023-17018-3
PMCID: PMC10621106
PMID: 37915007 [Indexed for MEDLINE]

Conflict of interest statement: The authors declare no competing financial 
interests. The authors declare no competing interests.
</reference>

<statements>
1. Copper and zinc associations were observational rather than proven therapeutic targets
2. In NHANES 2011–2016, 5,412 adults representing 76,479,702 individuals were followed for a mean of 5.85 years, with 96 cardiovascular deaths and 356 all-cause deaths
3. Compared with the lowest serum copper tertile, the highest tertile was associated with cardiovascular mortality (hazard ratio 7.06, 95% CI 1.85–26.96) and all-cause mortality (hazard ratio 2.84, 95% CI 1.66–4.87), with a linear dose-response relationship
4. A meta-analysis of three additional prospective cohorts including 13,189 patients confirmed an association between higher serum copper and cardiovascular disease (hazard ratio 2.08, 95% CI 1.63–2.65) and all-cause mortality (hazard ratio 1.89, 95% CI 1.58–2.25)
5. The authors explicitly state that causal relationships require further investigation
6. Copper and zinc are associated with cardiovascular risk in prospective cohorts, but no interventional outcome evidence is supplied
</statements>

Begin the assessment now. Output only the JSON list, without any conversational text or explanations.