You will be shown the abstract of a medical clinical trial report. Your task is to extract all the findings from this report into a JSON array. Each finding should contain the following five elements:

- Intervention: The medical intervention being tested. This should be a text span copied from the input passage.
- Comparator: The baseline against which the intervention is being evaluated. This should be a text span copied from the input passage. If no comparator is reported, set to `null`.
- Outcome: The medical outcome whose effect is being measured. This should be a text span copied from the input passage.
- Effect: The effect of the intervention on the outcome, relative to the comparator. The effect should be one of the following three values: ("significantly increased", "significantly decreased", "no significant difference").
- Evidence: The evidence for the effect. This should be a text span copied from the input passage.

Please format your output as a JSON array. Each entry in the output should be an array containing the 5 elements listed above, in the following order: [<intervention>, <comparator>, <outcome>, <effect>, <evidence>].

For example, an output with two findings might read:
```
[["aspirin", "placebo", "headache severity", "significantly decreased", "Mean headache severity was significantly decreased in the aspirin group compared to the placebo group (p < 0.05)."], ["aspirin", "placebo", "weight loss", "no significant difference", "We did not observe any difference in weight loss between the group given aspirin relative to the control group"]]
```

There are 4 finding(s) in the abstract below. Please extract them. Output only the JSON array with these 4 findings. Do not include any additional text.

Abstract:
ABSTRACT.INTRODUCTION: Our objective was to compare the bone and renal effects among HIV-infected patients randomized to abacavir or tenofovir-based combination anti-retroviral therapy.

ABSTRACT.METHODS: In an open-label randomized trial, HIV-infected patients were randomized to switch from zidovudine/lamivudine (AZT/3TC) to abacavir/lamivudine (ABC/3TC) or tenofovir/emtricitabine (TDF/FTC). We measured bone mass density (BMD) and bone turnover biomarkers (osteocalcin, osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), alkaline phosphatase, type I collagen cross-linked C-telopeptide (CTx), and osteoprotegerin). We assessed renal function by estimated creatinine clearance, plasma cystatin C, and urinary levels of creatinine, albumin, cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL). The changes from baseline in BMD and renal and bone biomarkers were compared across study arms.

ABSTRACT.RESULTS: Of 40 included patients, 35 completed 48 weeks of randomized therapy and follow up. BMD was measured in 33, 26, and 27 patients at baseline, week 24, and week 48, respectively. In TDF/FTC-treated patients we observed significant reductions from baseline in hip and lumbar spine BMD at week 24 (−1.8% and −2.5%) and week 48 (−2.1% and −2.1%), whereas BMD was stable in patients in the ABC/3TC arm. The changes from baseline in BMD were significantly different between study arms. All bone turnover biomarkers except osteoprotegerin increased in the TDF/FTC arm compared with the ABC/3TC arm, but early changes did not predict subsequent loss of BMD. Renal function parameters were similar between study arms although a small increase in NGAL was detected among TDF-treated patients.

ABSTRACT.CONCLUSION: Switching to TDF/FTC-based therapy led to decreases in BMD and increases in bone turnover markers compared with ABC/3TC-based treatment. No major difference in renal function was observed.

ABSTRACT.TRIAL REGISTRATION: Clinicaltrials.gov NCT00647244


Findings:
[["Abacavir/lamivudine (ABC/3TC) or tenofovir/emtricitabine (TDF/FTC)", "Zidovudine/lamivudine (AZT/3TC)", "Renal function parameters", "no significant difference", "Renal function parameters were similar between study arms although a small increase in NGAL was detected among TDF-treated patients."], ["Tenofovir/emtricitabine (TDF/FTC)", "Abacavir/lamivudine (ABC/3TC) ", "Hip bone mass density at weeks 24 and 48", "significantly decreased", "In TDF/FTC-treated patients we observed significant reductions from baseline in hip and lumbar spine BMD at week 24 (\u22121.8% and \u22122.5%) and week 48 (\u22122.1% and \u22122.1%), whereas BMD was stable in patients in the ABC/3TC arm."], ["Tenofovir/emtricitabine (TDF/FTC)", "Abacavir/lamivudine (ABC/3TC) ", "Lumbar spine bone mass density at weeks 24 and 48", "significantly decreased", "In TDF/FTC-treated patients we observed significant reductions from baseline in hip and lumbar spine BMD at week 24 (\u22121.8% and \u22122.5%) and week 48 (\u22122.1% and \u22122.1%), whereas BMD was stable in patients in the ABC/3TC arm."], ["Tenofovir/emtricitabine (TDF/FTC)", "Abacavir/lamivudine (ABC/3TC) ", "Bone turnover biomarkers (except osteoprotegerin)", "significantly increased", "All bone turnover biomarkers except osteoprotegerin increased in the TDF/FTC arm compared with the ABC/3TC arm, but early changes did not predict subsequent loss of BMD."]]